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gord(at)thedampub.ca
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 Posted: Tue Jul 21, 2015 2:28 pm Post subject: YAK-50 landing gear actuators overhaul time. |
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It is time to share an adrenaline moment and some good luck in my YAK 50.
As part of my airshow routine I do a final pass with the landing gear down. I put the gear down below 150 kph. I did not get a green light on the right side. The light tested OK. I asked the airboss if the gear was down….yes it was. It was the end of the routine and I had a 10 minute flight back to Owen Sound airport. Wondering about this, should I leave them, should I retract them, I decided to retract them. At the airport I put the gear down, got 2 green lights and landed uneventfully.
We checked the gear visually and the micro switches. That is when we found out they we wired backwards, but they were working fine. Left means right. I guess they were facing backwards during installation. A puzzle.
I flew the air show the next day and all was routine……. except the weather.
The following week I flew another short demo flight, put the gear down and no right green light. Since I had good luck last time retracting and extending I did the same. No green light on the right side again, meaning it was a downlock problem on the left gear. The light out checked OK. The air pressure was now just under 3. The emergency system was 5.5. The ground confirmed both gear were down.
Should I use the emergency system? I thought long and fast since there was not a lot of fuel available and it was a very busy airport scene. I had sufficient air pressure to extend the gear with the main system gear. Why then use an alternate air system? To me, it was a downlock problem. Would the extra pressure help that? I was not sure. So I decided to try and jar the gear into the locked position first.
I got the speed back to about 110 kph getting the nose up and angle gear forward, then bounced the left gear on the runway ready for an immediate go-around. I heard a ‘snap’ caught the green light out of the corner of my eye and landed with 2 green lights. Ground observers confirmed the left wheel moved back about an inch or two, then snapped forward.
I called Dennis, as I always do when I have a problem, and as usual, he had the solution. Pull the actuators and send them to Jill at M14P Inc. So we did.
We got the actuators back and finally got them installed. Not an easy job. The gear swing is certainly a lot more violent now. It was a good thing that we had one person holding each wing tip down on the jacks during the swing. We haven’t bothered to rewire them yet and I have not flown the airplane yet.
I spoke to Jill and the first thing she said was “You dodged a bullet”.
Apparently, during the initial test, they blew the end off the left actuator with only 300psi.
I am so glad I did not use the emergency system and ram in all 850 psi. If the end had blown off in the air … what a mess.
Jill put on the last remaining new actuator cap and they are looking for more supply.
So that is my story. Comments criticisms are most welcome. That is the way we all learn.
I don’t have all the answers but I sure had some good luck this time.
And yes we will be removing the actuators in 5 years for another overhaul.
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dsavarese0812(at)bellsout
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| Posted: Tue Jul 21, 2015 5:47 pm Post subject: YAK-50 landing gear actuators overhaul time. |
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Gordon, it's not necessary to rewire the gear lights. Simply unscrew the lamp holder knurled nuts, slide the lamp holders back thru the instrument panel and swap their positions. Dennis
Sent from my iPhone
| Quote: | On Jul 21, 2015, at 5:24 PM, Gordon Price <gord(at)thedampub.ca> wrote:
It is time to share an adrenaline moment and some good luck in my YAK 50.
As part of my airshow routine I do a final pass with the landing gear down. I put the gear down below 150 kph. I did not get a green light on the right side. The light tested OK. I asked the airboss if the gear was down….yes it was. It was the end of the routine and I had a 10 minute flight back to Owen Sound airport. Wondering about this, should I leave them, should I retract them, I decided to retract them. At the airport I put the gear down, got 2 green lights and landed uneventfully.
We checked the gear visually and the micro switches. That is when we found out they we wired backwards, but they were working fine. Left means right. I guess they were facing backwards during installation. A puzzle.
I flew the air show the next day and all was routine……. except the weather.
The following week I flew another short demo flight, put the gear down and no right green light. Since I had good luck last time retracting and extending I did the same. No green light on the right side again, meaning it was a downlock problem on the left gear. The light out checked OK. The air pressure was now just under 3. The emergency system was 5.5. The ground confirmed both gear were down.
Should I use the emergency system? I thought long and fast since there was not a lot of fuel available and it was a very busy airport scene. I had sufficient air pressure to extend the gear with the main system gear. Why then use an alternate air system? To me, it was a downlock problem. Would the extra pressure help that? I was not sure. So I decided to try and jar the gear into the locked position first.
I got the speed back to about 110 kph getting the nose up and angle gear forward, then bounced the left gear on the runway ready for an immediate go-around. I heard a ‘snap’ caught the green light out of the corner of my eye and landed with 2 green lights. Ground observers confirmed the left wheel moved back about an inch or two, then snapped forward.
I called Dennis, as I always do when I have a problem, and as usual, he had the solution. Pull the actuators and send them to Jill at M14P Inc. So we did.
We got the actuators back and finally got them installed. Not an easy job. The gear swing is certainly a lot more violent now. It was a good thing that we had one person holding each wing tip down on the jacks during the swing. We haven’t bothered to rewire them yet and I have not flown the airplane yet.
I spoke to Jill and the first thing she said was “You dodged a bullet”.
Apparently, during the initial test, they blew the end off the left actuator with only 300psi.
I am so glad I did not use the emergency system and ram in all 850 psi. If the end had blown off in the air … what a mess.
Jill put on the last remaining new actuator cap and they are looking for more supply.
So that is my story. Comments criticisms are most welcome. That is the way we all learn.
I don’t have all the answers but I sure had some good luck this time.
And yes we will be removing the actuators in 5 years for another overhaul.
|
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gord(at)thedampub.ca
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| Posted: Tue Jul 21, 2015 6:06 pm Post subject: YAK-50 landing gear actuators overhaul time. |
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Why is it that I can’t think of something so simple!
Thanks Dennis
| Quote: | On Jul 21, 2015, at 9:42 PM, A. Dennis Savarese <dsavarese0812(at)bellsouth.net> wrote:
Gordon, it's not necessary to rewire the gear lights. Simply unscrew the lamp holder knurled nuts, slide the lamp holders back thru the instrument panel and swap their positions. Dennis
Sent from my iPhone
> On Jul 21, 2015, at 5:24 PM, Gordon Price <gord(at)thedampub.ca> wrote:
>
>
>
> It is time to share an adrenaline moment and some good luck in my YAK 50.
>
> As part of my airshow routine I do a final pass with the landing gear down. I put the gear down below 150 kph. I did not get a green light on the right side. The light tested OK. I asked the airboss if the gear was down….yes it was. It was the end of the routine and I had a 10 minute flight back to Owen Sound airport. Wondering about this, should I leave them, should I retract them, I decided to retract them. At the airport I put the gear down, got 2 green lights and landed uneventfully.
>
> We checked the gear visually and the micro switches. That is when we found out they we wired backwards, but they were working fine. Left means right. I guess they were facing backwards during installation. A puzzle.
>
> I flew the air show the next day and all was routine……. except the weather.
>
> The following week I flew another short demo flight, put the gear down and no right green light. Since I had good luck last time retracting and extending I did the same. No green light on the right side again, meaning it was a downlock problem on the left gear. The light out checked OK. The air pressure was now just under 3. The emergency system was 5.5. The ground confirmed both gear were down.
>
> Should I use the emergency system? I thought long and fast since there was not a lot of fuel available and it was a very busy airport scene. I had sufficient air pressure to extend the gear with the main system gear. Why then use an alternate air system? To me, it was a downlock problem. Would the extra pressure help that? I was not sure. So I decided to try and jar the gear into the locked position first.
>
> I got the speed back to about 110 kph getting the nose up and angle gear forward, then bounced the left gear on the runway ready for an immediate go-around. I heard a ‘snap’ caught the green light out of the corner of my eye and landed with 2 green lights. Ground observers confirmed the left wheel moved back about an inch or two, then snapped forward.
>
> I called Dennis, as I always do when I have a problem, and as usual, he had the solution. Pull the actuators and send them to Jill at M14P Inc. So we did.
>
> We got the actuators back and finally got them installed. Not an easy job. The gear swing is certainly a lot more violent now. It was a good thing that we had one person holding each wing tip down on the jacks during the swing. We haven’t bothered to rewire them yet and I have not flown the airplane yet.
>
> I spoke to Jill and the first thing she said was “You dodged a bullet”.
>
> Apparently, during the initial test, they blew the end off the left actuator with only 300psi.
>
> I am so glad I did not use the emergency system and ram in all 850 psi. If the end had blown off in the air … what a mess.
>
> Jill put on the last remaining new actuator cap and they are looking for more supply.
>
> So that is my story. Comments criticisms are most welcome. That is the way we all learn.
>
> I don’t have all the answers but I sure had some good luck this time.
>
> And yes we will be removing the actuators in 5 years for another overhaul.
>
>
>
>
>
>
|
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jan.mevis(at)informavia.b
Guest
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| Posted: Tue Jul 21, 2015 10:11 pm Post subject: YAK-50 landing gear actuators overhaul time. |
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Hi Gordon,
I always listen carefully when the gear extends.
You can hear (or feel) the locking so I don't rely only upon the green
lights.
These Yak 50 actuators are one of the issues where the 50 is very
different compared to the Yak 52.
IMHO the system has been improved on the 52. The 52 has a separate small
locking actuator.
On the 50, the whole actuator moves for locking and unlocking. Tuning this
is not so easy.
The original Russian maintenance manual (DOSAAF 1979) says that you may
only have three complete swings using the emergency bottle.
After that, a complete overhaul of the landing gear is imperative.
I had to use it once when the main pressure feed line collapsed (between
the snot bottle and the cross).
The full unrestricted blow of the emergency bottle is indeed impressive.
BR,
Jan (Yak 50 F-AZUK).
On 22/07/15 04:01, "Gordon Price" <owner-yak-list-server(at)matronics.com on
behalf of gord(at)thedampub.ca> wrote:
| Quote: |
Why is it that I cant think of something so simple!
Thanks Dennis
> On Jul 21, 2015, at 9:42 PM, A. Dennis Savarese
><dsavarese0812(at)bellsouth.net> wrote:
>
>
><dsavarese0812(at)bellsouth.net>
>
> Gordon, it's not necessary to rewire the gear lights. Simply unscrew
>the lamp holder knurled nuts, slide the lamp holders back thru the
>instrument panel and swap their positions. Dennis
>
> Sent from my iPhone
>
>> On Jul 21, 2015, at 5:24 PM, Gordon Price <gord(at)thedampub.ca> wrote:
>>
>>
>>
>> It is time to share an adrenaline moment and some good luck in my YAK
>>50.
>>
>> As part of my airshow routine I do a final pass with the landing gear
>>down. I put the gear down below 150 kph. I did not get a green light
>>on the right side. The light tested OK. I asked the airboss if the
>>gear was down.yes it was. It was the end of the routine and I had a
>>10 minute flight back to Owen Sound airport. Wondering about this,
>>should I leave them, should I retract them, I decided to retract them.
>>At the airport I put the gear down, got 2 green lights and landed
>>uneventfully.
>>
>> We checked the gear visually and the micro switches. That is when we
>>found out they we wired backwards, but they were working fine. Left
>>means right. I guess they were facing backwards during installation. A
>>puzzle.
>>
>> I flew the air show the next day and all was routine. except the
>>weather.
>>
>> The following week I flew another short demo flight, put the gear down
>>and no right green light. Since I had good luck last time retracting
>>and extending I did the same. No green light on the right side again,
>>meaning it was a downlock problem on the left gear. The light out
>>checked OK. The air pressure was now just under 3. The emergency
>>system was 5.5. The ground confirmed both gear were down.
>>
>> Should I use the emergency system? I thought long and fast since
>>there was not a lot of fuel available and it was a very busy airport
>>scene. I had sufficient air pressure to extend the gear with the main
>>system gear. Why then use an alternate air system? To me, it was a
>>downlock problem. Would the extra pressure help that? I was not sure.
>>So I decided to try and jar the gear into the locked position first.
>>
>> I got the speed back to about 110 kph getting the nose up and angle
>>gear forward, then bounced the left gear on the runway ready for an
>>immediate go-around. I heard a snap caught the green light out of
>>the corner of my eye and landed with 2 green lights. Ground observers
>>confirmed the left wheel moved back about an inch or two, then snapped
>>forward.
>>
>> I called Dennis, as I always do when I have a problem, and as usual,
>>he had the solution. Pull the actuators and send them to Jill at M14P
>>Inc. So we did.
>>
>> We got the actuators back and finally got them installed. Not an easy
>>job. The gear swing is certainly a lot more violent now. It was a good
>>thing that we had one person holding each wing tip down on the jacks
>>during the swing. We havent bothered to rewire them yet and I have
>>not flown the airplane yet.
>>
>> I spoke to Jill and the first thing she said was You dodged a
>>bullet.
>>
>> Apparently, during the initial test, they blew the end off the left
>>actuator with only 300psi.
>>
>> I am so glad I did not use the emergency system and ram in all 850
>>psi. If the end had blown off in the air what a mess.
>>
>> Jill put on the last remaining new actuator cap and they are looking
>>for more supply.
>>
>> So that is my story. Comments criticisms are most welcome. That is
>>the way we all learn.
>>
>> I dont have all the answers but I sure had some good luck this time.
>>
>> And yes we will be removing the actuators in 5 years for another
>>overhaul.
>>
>>
>>
>>
>>
>>
>
>
>
>
>
|
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gord(at)thedampub.ca
Guest
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| Posted: Wed Jul 22, 2015 3:47 am Post subject: YAK-50 landing gear actuators overhaul time. |
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Thank you Jan. Very interesting about only 3 emergency extensions. Im wondering where to look for the damage caused by this. Also, we did not tune the gear since the actuators were sent back to us the same length as when went sent them out. Is there something else we should be doing? We had quite a job getting the right down lock microswitch working properly again. This is SN 01 and there are 3 different sets of holes for the microswitch. Unfortunately we could not remove the actuators without removing the downlink micro switches. That was the worst part..getting them back in.
| Quote: | On Jul 22, 2015, at 2:07 AM, Jan Mevis <jan.mevis(at)informavia.be> wrote:
Hi Gordon,
I always listen carefully when the gear extends.
You can hear (or feel) the locking so I don't rely only upon the green
lights.
These Yak 50 actuators are one of the issues where the 50 is very
different compared to the Yak 52.
IMHO the system has been improved on the 52. The 52 has a separate small
locking actuator.
On the 50, the whole actuator moves for locking and unlocking. Tuning this
is not so easy.
The original Russian maintenance manual (DOSAAF 1979) says that you may
only have three complete swings using the emergency bottle.
After that, a complete overhaul of the landing gear is imperative.
I had to use it once when the main pressure feed line collapsed (between
the snot bottle and the cross).
The full unrestricted blow of the emergency bottle is indeed impressive.
BR,
Jan (Yak 50 F-AZUK).
|
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GeorgeCoy
Joined: 02 Dec 2010
Posts: 310
|
| Posted: Wed Jul 22, 2015 4:09 am Post subject: YAK-50 landing gear actuators overhaul time. |
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|
Hmmm, So when the emergency gear extension is tested at very annual
condition extension, then it gets rebuilt every third year? I guess most of
us missed that memo.
George
--
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jan.mevis(at)informavia.b
Guest
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| Posted: Wed Jul 22, 2015 5:35 am Post subject: YAK-50 landing gear actuators overhaul time. |
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|
No, testing is no issue, but with air from the emergency system we don't
let it go the whole way.
I would be very scared doing that with the plane on jacks. The odds are
that it would jump off the jacks.
The one time that I had to use the emergency system in flight, I remember
that it was a very violent experience.
Impossible to not notice it, the gear gets slammed down with so much force
and the whole plane shaked.
The Lithuanian mechanic that services my Yak 50 does check the emergency
system at each annual but he cuts the air supply before it's fully
developped.
Anyway, the Russian DOSAAF manual says that the main gear of the 50 should
be rebuilt after 3 uses of the emergency system.
Not only the actuators, the whole gear.
We sometimes forget that the scheduled lifetime of the Yak 50 was rather
short. The 50 was easily destined to be scrapped after certain mishaps.
Of course we do test the normal system each year and then we do have the
gear retract and extend several times, the whole way.
That's no problem.
We also do check the bottles each year.
BR,
Jan
On 22/07/15 14:05, "George S. Coy" <owner-yak-list-server(at)matronics.com on
behalf of george.coy(at)gmail.com> wrote:
[quote]
Hmmm, So when the emergency gear extension is tested at very annual
condition extension, then it gets rebuilt every third year? I guess most
of
us missed that memo.
George
--
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jan.mevis(at)informavia.b
Guest
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| Posted: Wed Jul 22, 2015 5:47 am Post subject: YAK-50 landing gear actuators overhaul time. |
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Hi Gordon,
Tuning is not the right expression, sorry (but English is not my native
language).
Re-installing the actuators is demanding: there are small levers that
connect between the actuators and the wing (if I remember well, it has
been some time).
It is possible that on your plane (being SN01 !!!! Waw) it is slightly
different.
I remember that there has to be some specific "play" for these levers
otherwise it could cause a malfunctioning under circumstances.
Bottomline: I have it serviced by a Lithuanian mechanic.
Maybe you should try and find a mechanic that has experience in doing
this?
Next time that you go flying, listen to the gear when it extends, you
should hear or feel it locking.
BR,
Jan
On 22/07/15 13:43, "Gordon Price" <owner-yak-list-server(at)matronics.com on
behalf of gord(at)thedampub.ca> wrote:
| Quote: |
Thank you Jan. Very interesting about only 3 emergency extensions.
Im wondering where to look for the damage caused by this. Also, we did
not tune the gear since the actuators were sent back to us the same
length as when went sent them out. Is there something else we should be
doing? We had quite a job getting the right down lock microswitch
working properly again. This is SN 01 and there are 3 different sets of
holes for the microswitch. Unfortunately we could not remove the
actuators without removing the downlink micro switches. That was the
worst part..getting them back in.
> On Jul 22, 2015, at 2:07 AM, Jan Mevis <jan.mevis(at)informavia.be> wrote:
>
>
>
> Hi Gordon,
>
> I always listen carefully when the gear extends.
> You can hear (or feel) the locking so I don't rely only upon the green
> lights.
> These Yak 50 actuators are one of the issues where the 50 is very
> different compared to the Yak 52.
> IMHO the system has been improved on the 52. The 52 has a separate small
> locking actuator.
> On the 50, the whole actuator moves for locking and unlocking. Tuning
>this
> is not so easy.
> The original Russian maintenance manual (DOSAAF 1979) says that you may
> only have three complete swings using the emergency bottle.
> After that, a complete overhaul of the landing gear is imperative.
> I had to use it once when the main pressure feed line collapsed (between
> the snot bottle and the cross).
> The full unrestricted blow of the emergency bottle is indeed impressive.
>
>
> BR,
>
> Jan (Yak 50 F-AZUK).
>
|
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McFly
Joined: 21 May 2012
Posts: 101
Location: Scottsdale, AZ
|
| Posted: Wed Jul 22, 2015 7:39 am Post subject: YAK-50 landing gear actuators overhaul time. |
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|
Jan,
I would love to get a copy of that MX manual.
Please email me directly. The info is below.
Todd McCutchanT-34A & Yak-50
Cell: (260) 402-1740
E-mail: todd(at)fastaircraft.com (todd(at)fastaircraft.com)
www.fastaircraft.com
On Jul 22, 2015, at 9:32 AM, Jan Mevis <jan.mevis(at)informavia.be (jan.mevis(at)informavia.be)> wrote:
[quote]--> Yak-List message posted by: Jan Mevis <jan.mevis(at)informavia.be (jan.mevis(at)informavia.be)>
No, testing is no issue, but with air from the emergency system we don't
let it go the whole way.
I would be very scared doing that with the plane on jacks. The odds are
that it would jump off the jacks.
The one time that I had to use the emergency system in flight, I remember
that it was a very violent experience.
Impossible to not notice it, the gear gets slammed down with so much force
and the whole plane shaked.
The Lithuanian mechanic that services my Yak 50 does check the emergency
system at each annual but he cuts the air supply before it's fully
developped.
Anyway, the Russian DOSAAF manual says that the main gear of the 50 should
be rebuilt after 3 uses of the emergency system.
Not only the actuators, the whole gear.
We sometimes forget that the scheduled lifetime of the Yak 50 was rather
short. The 50 was easily destined to be scrapped after certain mishaps.
Of course we do test the normal system each year and then we do have the
gear retract and extend several times, the whole way.
That's no problem.
We also do check the bottles each year.
BR,
Jan
On 22/07/15 14:05, "George S. Coy" <owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) on
behalf of george.coy(at)gmail.com (george.coy(at)gmail.com)> wrote:
[quote]--> Yak-List message posted by: "George S. Coy" <george.coy(at)gmail.com (george.coy(at)gmail.com)>
Hmmm, So when the emergency gear extension is tested at very annual
condition extension, then it gets rebuilt every third year? I guess most
of
us missed that memo.
George
--
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_________________
Todd McCutchan
Fast Aircraft
T-34A - N134FA
KDVT Hangar 33-13
Cell - 260.402.1740
Email: todd@fastaircraft.com
Skype: tmccutchan
Web: www.fastaircraft.com & www.flyams.com |
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mark.bitterlich(at)navy.m
Guest
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| Posted: Wed Jul 22, 2015 8:33 am Post subject: YAK-50 landing gear actuators overhaul time. |
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Jan,
Comment: I have to politely disagree with you about "feeling the gear come down and lock". Yes, you can hear it come down. But you sure can NOT hear it lock. That "thump" you feel is NOT the gear locking. It is the gear actuator reaching maximum travel and HOPEFULLY the gear moving far enough forward to allow the down-lock to engage
The simple fact is that the gear lights on the 50 only indicate that the legs have moved past a certain position. Thus if everything worked correctly the gear SHOULD have locked. ALWAYS CHECK THE LIGHTS!
The GEAR ACTUATOR on the 50 is what is actually on a mechanism that causes it to move when air is applied to lower the gear. These are the "levers" you were thinking about. This movement translates to the UNLOCK mechanism so that the gear can come off the UP locks and start downward movement.
As for locking DOWN .... you can have the aircraft on jacks, with the gear leg unlocked and hanging, and no air pressure at all, or even with the actually totally REMOVED. All you have to do is gently push on the gear leg and the locking mechanism will engage, and you can actually SEE it if the fiberglass cover is removed. You can reach in there with a screw driver (flat head) push down on the locking pin and unlock the DOWNLOCK and it will swing back to just hanging again.
So the point is, the UP-LOCK only requires the actuator itself to MOVE on concentric mounting slots which UNLOCKS the UPLOCK, the air pressure than pushes the gear down far enough to where the gear DOWNLOCK will engage. The actual movement of the pins and wedge that LOCKS THE GEAR DOWN is actually not a very loud sound. The "movement" of the whole actuator is only there to unlock the UPLOCK, after that, the actuator plunger shaft pushes the gear down to final extension.
Final thought on this. ALWAYS ALWAYS LOOK AT THE LIGHTS! I got into the same habit Jan did by listening to the THUMP of the gear coming down. And then one time the gear went THUMP THUMP and the left one was NOT LOCKED and the left light was seen later to NOT BE ON. So this is not theory, it happened. On the Conditional, it is best to turn all the air off, then lower the gear (on jacks obviously), the gear will unlock and not go totally down to lock. Then with the cover removed over the top of the landing gear strut, gently PUSH on the gear leg while someone is WATCHING the gear light! You will see and feel the gear lock down and that is when the light should come on and NOT BEFORE. If it does, adjust the switch.
Emergency gear extensions have no restrictor in the gear hose. Thus 735 PSI of air is applied ALL AT ONCE with full flow potential. Not only can it make the aircraft jump off the jacks, but it also can blow out the chevron seals. The new chevron seals installed in rebuilt actuators are much better than the originals that the Russians used, which usually harden and then turn into gel when someone tells you to inject "stuff" into the air system after it sat for a few years. Use Dennis's procedure for testing emergency. Then realize too that you will have to reset the check valves on the bottom of the actuators. Not hard. See his procedure. I made up my own, but his is better.
Bottom line ... do a careful check on the downlock by hand. Check to make sure the switches are adjusted properly so they go on when the gear is LOCKED and not before.
Then listen for the THUMP THUMP, but ALWAYS CHECK THE LIGHTS TOO!
Mark
--
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mark.bitterlich(at)navy.m
Guest
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| Posted: Wed Jul 22, 2015 8:51 am Post subject: YAK-50 landing gear actuators overhaul time. |
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When you replaced the gear actuators, did anyone tell you about the restrictor washers that fit into the air line connecting to the up and down side normal hoses?
If they did not, then be aware that they fall out very easily and get lost. Did you make sure you put them back in exactly as they came out?
The only reason I mention this is because of your comment about the gear coming down much more violently now.
If you lost those washers with the small holes through them, then your gear will swing at the same speed it would if emergency air was used and that is a very bad thing.
I really hope you know what I am talking about here. ..
Next:
If you lower the gear and a light does not come on, put your gear handle in the middle position. This isolates the landing gear actuators. Then fly around and wait until main air pressure builds back to 50 ATMOS. Select DOWN on the main gear handle again and see if the light comes on. If it does not, then use Emergency Air PROCEDURES. If it still does not come down, close the emergency air valve, fly around until the pressure builds back up on the emergency bottle and then TRY EMERGENCY PROCEDURES AGAIN! Note: Yak-50 pressurizes BOTH main and emergency bottles from the engine compressor, unlike the 52.
People looking at the gear cannot tell if it is really locked when you are flying, only that it "looks down". It would take a real YAK-50 expert to carefully see the angle of that gear to even make an educated guess. Chevron seal failure in the actuators is common. If you were to raise the gear at this point, what little is left can turn into slush or pieces and then you are looking at a gear up landing. Bottom line, yes, you should have used the emergency air procedures (read them carefully). If even THAT fails, having the gear handle in the middle, close the emergency air bottle valve, fly around and BOTH bottles will re-pressurize. Try the emergency procedure again! I'd keep doing that until I almost ran out of gas.
Good job on the "bounce" on the runway. The only reason it worked was that there was still air in the system pushing on that actuator. With a total chevron seal failure, it would not have.
Mark
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jan.mevis(at)informavia.b
Guest
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| Posted: Wed Jul 22, 2015 9:31 am Post subject: YAK-50 landing gear actuators overhaul time. |
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Hi Todd,
I'll try to make some copies, but it's an old book, so it'll take some time.
Jan
From: <owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)> on behalf of Todd McCutchan <todd(at)fastaircraft.com (todd(at)fastaircraft.com)>
Reply-To: "yak-list(at)matronics.com (yak-list(at)matronics.com)" <yak-list(at)matronics.com (yak-list(at)matronics.com)>
Date: Wednesday 22 July 2015 17:35
To: "yak-list(at)matronics.com (yak-list(at)matronics.com)" <yak-list(at)matronics.com (yak-list(at)matronics.com)>
Subject: Re: YAK-50 landing gear actuators overhaul time.
Jan,
I would love to get a copy of that MX manual.
Please email me directly. The info is below.
Todd McCutchanT-34A & Yak-50
Cell: (260) 402-1740
E-mail: todd(at)fastaircraft.com (todd(at)fastaircraft.com)
www.fastaircraft.com
On Jul 22, 2015, at 9:32 AM, Jan Mevis <jan.mevis(at)informavia.be (jan.mevis(at)informavia.be)> wrote:
[quote]--> Yak-List message posted by: Jan Mevis <jan.mevis(at)informavia.be (jan.mevis(at)informavia.be)>
No, testing is no issue, but with air from the emergency system we don't
let it go the whole way.
I would be very scared doing that with the plane on jacks. The odds are
that it would jump off the jacks.
The one time that I had to use the emergency system in flight, I remember
that it was a very violent experience.
Impossible to not notice it, the gear gets slammed down with so much force
and the whole plane shaked.
The Lithuanian mechanic that services my Yak 50 does check the emergency
system at each annual but he cuts the air supply before it's fully
developped.
Anyway, the Russian DOSAAF manual says that the main gear of the 50 should
be rebuilt after 3 uses of the emergency system.
Not only the actuators, the whole gear.
We sometimes forget that the scheduled lifetime of the Yak 50 was rather
short. The 50 was easily destined to be scrapped after certain mishaps.
Of course we do test the normal system each year and then we do have the
gear retract and extend several times, the whole way.
That's no problem.
We also do check the bottles each year.
BR,
Jan
On 22/07/15 14:05, "George S. Coy" <owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) on
behalf of george.coy(at)gmail.com (george.coy(at)gmail.com)> wrote:
[quote]--> Yak-List message posted by: "George S. Coy" <george.coy(at)gmail.com (george.coy(at)gmail.com)>
Hmmm, So when the emergency gear extension is tested at very annual
condition extension, then it gets rebuilt every third year? I guess most
of
us missed that memo.
George
--
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jan.mevis(at)informavia.b
Guest
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| Posted: Wed Jul 22, 2015 9:34 am Post subject: YAK-50 landing gear actuators overhaul time. |
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|
Thanks Mark. Of course I always check the lights. I also carefully do the
lamp test before each flight.
I appreciate your correction!
Jan
On 22/07/15 18:29, "Bitterlich, Mark G CIV NAVAIR, WD"
<owner-yak-list-server(at)matronics.com on behalf of
mark.bitterlich(at)navy.mil> wrote:
[quote]
<mark.bitterlich(at)navy.mil>
Jan,
Comment: I have to politely disagree with you about "feeling the gear
come down and lock". Yes, you can hear it come down. But you sure can
NOT hear it lock. That "thump" you feel is NOT the gear locking. It is
the gear actuator reaching maximum travel and HOPEFULLY the gear moving
far enough forward to allow the down-lock to engage
The simple fact is that the gear lights on the 50 only indicate that the
legs have moved past a certain position. Thus if everything worked
correctly the gear SHOULD have locked. ALWAYS CHECK THE LIGHTS!
The GEAR ACTUATOR on the 50 is what is actually on a mechanism that
causes it to move when air is applied to lower the gear. These are the
"levers" you were thinking about. This movement translates to the UNLOCK
mechanism so that the gear can come off the UP locks and start downward
movement.
As for locking DOWN .... you can have the aircraft on jacks, with the
gear leg unlocked and hanging, and no air pressure at all, or even with
the actually totally REMOVED. All you have to do is gently push on the
gear leg and the locking mechanism will engage, and you can actually SEE
it if the fiberglass cover is removed. You can reach in there with a
screw driver (flat head) push down on the locking pin and unlock the
DOWNLOCK and it will swing back to just hanging again.
So the point is, the UP-LOCK only requires the actuator itself to MOVE on
concentric mounting slots which UNLOCKS the UPLOCK, the air pressure than
pushes the gear down far enough to where the gear DOWNLOCK will engage.
The actual movement of the pins and wedge that LOCKS THE GEAR DOWN is
actually not a very loud sound. The "movement" of the whole actuator is
only there to unlock the UPLOCK, after that, the actuator plunger shaft
pushes the gear down to final extension.
Final thought on this. ALWAYS ALWAYS LOOK AT THE LIGHTS! I got into
the same habit Jan did by listening to the THUMP of the gear coming down.
And then one time the gear went THUMP THUMP and the left one was NOT
LOCKED and the left light was seen later to NOT BE ON. So this is not
theory, it happened. On the Conditional, it is best to turn all the air
off, then lower the gear (on jacks obviously), the gear will unlock and
not go totally down to lock. Then with the cover removed over the top
of the landing gear strut, gently PUSH on the gear leg while someone is
WATCHING the gear light! You will see and feel the gear lock down and
that is when the light should come on and NOT BEFORE. If it does,
adjust the switch.
Emergency gear extensions have no restrictor in the gear hose. Thus 735
PSI of air is applied ALL AT ONCE with full flow potential. Not only can
it make the aircraft jump off the jacks, but it also can blow out the
chevron seals. The new chevron seals installed in rebuilt actuators are
much better than the originals that the Russians used, which usually
harden and then turn into gel when someone tells you to inject "stuff"
into the air system after it sat for a few years. Use Dennis's
procedure for testing emergency. Then realize too that you will have to
reset the check valves on the bottom of the actuators. Not hard. See
his procedure. I made up my own, but his is better.
Bottom line ... do a careful check on the downlock by hand. Check to
make sure the switches are adjusted properly so they go on when the gear
is LOCKED and not before.
Then listen for the THUMP THUMP, but ALWAYS CHECK THE LIGHTS TOO!
Mark
--
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mark.bitterlich(at)navy.m
Guest
|
| Posted: Wed Jul 22, 2015 10:42 am Post subject: YAK-50 landing gear actuators overhaul time. |
|
|
Sorry if I misunderstood Jan!
________________________________________
From: owner-yak-list-server(at)matronics.com [owner-yak-list-server(at)matronics.com] on behalf of Jan Mevis [jan.mevis(at)informavia.be]
Sent: Wednesday, July 22, 2015 1:31 PM
To: yak-list(at)matronics.com
Subject: Re: YAK-50 landing gear actuators overhaul time.
Thanks Mark. Of course I always check the lights. I also carefully do the
lamp test before each flight.
I appreciate your correction!
Jan
On 22/07/15 18:29, "Bitterlich, Mark G CIV NAVAIR, WD"
<owner-yak-list-server(at)matronics.com on behalf of
mark.bitterlich(at)navy.mil> wrote:
[quote]
<mark.bitterlich(at)navy.mil>
Jan,
Comment: I have to politely disagree with you about "feeling the gear
come down and lock". Yes, you can hear it come down. But you sure can
NOT hear it lock. That "thump" you feel is NOT the gear locking. It is
the gear actuator reaching maximum travel and HOPEFULLY the gear moving
far enough forward to allow the down-lock to engage
The simple fact is that the gear lights on the 50 only indicate that the
legs have moved past a certain position. Thus if everything worked
correctly the gear SHOULD have locked. ALWAYS CHECK THE LIGHTS!
The GEAR ACTUATOR on the 50 is what is actually on a mechanism that
causes it to move when air is applied to lower the gear. These are the
"levers" you were thinking about. This movement translates to the UNLOCK
mechanism so that the gear can come off the UP locks and start downward
movement.
As for locking DOWN .... you can have the aircraft on jacks, with the
gear leg unlocked and hanging, and no air pressure at all, or even with
the actually totally REMOVED. All you have to do is gently push on the
gear leg and the locking mechanism will engage, and you can actually SEE
it if the fiberglass cover is removed. You can reach in there with a
screw driver (flat head) push down on the locking pin and unlock the
DOWNLOCK and it will swing back to just hanging again.
So the point is, the UP-LOCK only requires the actuator itself to MOVE on
concentric mounting slots which UNLOCKS the UPLOCK, the air pressure than
pushes the gear down far enough to where the gear DOWNLOCK will engage.
The actual movement of the pins and wedge that LOCKS THE GEAR DOWN is
actually not a very loud sound. The "movement" of the whole actuator is
only there to unlock the UPLOCK, after that, the actuator plunger shaft
pushes the gear down to final extension.
Final thought on this. ALWAYS ALWAYS LOOK AT THE LIGHTS! I got into
the same habit Jan did by listening to the THUMP of the gear coming down.
And then one time the gear went THUMP THUMP and the left one was NOT
LOCKED and the left light was seen later to NOT BE ON. So this is not
theory, it happened. On the Conditional, it is best to turn all the air
off, then lower the gear (on jacks obviously), the gear will unlock and
not go totally down to lock. Then with the cover removed over the top
of the landing gear strut, gently PUSH on the gear leg while someone is
WATCHING the gear light! You will see and feel the gear lock down and
that is when the light should come on and NOT BEFORE. If it does,
adjust the switch.
Emergency gear extensions have no restrictor in the gear hose. Thus 735
PSI of air is applied ALL AT ONCE with full flow potential. Not only can
it make the aircraft jump off the jacks, but it also can blow out the
chevron seals. The new chevron seals installed in rebuilt actuators are
much better than the originals that the Russians used, which usually
harden and then turn into gel when someone tells you to inject "stuff"
into the air system after it sat for a few years. Use Dennis's
procedure for testing emergency. Then realize too that you will have to
reset the check valves on the bottom of the actuators. Not hard. See
his procedure. I made up my own, but his is better.
Bottom line ... do a careful check on the downlock by hand. Check to
make sure the switches are adjusted properly so they go on when the gear
is LOCKED and not before.
Then listen for the THUMP THUMP, but ALWAYS CHECK THE LIGHTS TOO!
Mark
--
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gord(at)thedampub.ca
Guest
|
| Posted: Wed Jul 22, 2015 1:52 pm Post subject: YAK-50 landing gear actuators overhaul time. |
|
|
Mark.
Thank you so much for your post. I am learning a lot.
The restrictor washers are still in the lines OK. Nothing fell out. I think the reason it comes down harder is that basically the actuators were seized. We could not retract them at all to ship them.
Re: putting the lever in the neutral position and fly around building up pressure…good to know if there is another event. In this case though I had very little time since I only had 15 litres left in the tanks and there was a lot of uncontrolled traffic around the airport.
Based on what you said I don’t think I would retract the gear after no green light again. Now I know why. Thank you.
I am still not sure that, given the problem that I had ( no green light) and the one I was not aware of at the time ( the end blowing off the actuator at MP4 Inc) that using the emergency system would have been a good idea. If I used the full pressure of the emergency system and the end blew off the actuator, what sort of situation would I have been facing? In my mind it would have been one gear locked down and the other blowing in the wind with no pressure. Am I wrong?
I am glad we are able to discuss this after the fact … and there was no damage. Luck was on my side.
Best regards
Gord
| Quote: | On Jul 22, 2015, at 12:48 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil> wrote:
When you replaced the gear actuators, did anyone tell you about the restrictor washers that fit into the air line connecting to the up and down side normal hoses?
If they did not, then be aware that they fall out very easily and get lost. Did you make sure you put them back in exactly as they came out?
The only reason I mention this is because of your comment about the gear coming down much more violently now.
If you lost those washers with the small holes through them, then your gear will swing at the same speed it would if emergency air was used and that is a very bad thing.
I really hope you know what I am talking about here. ..
Next:
If you lower the gear and a light does not come on, put your gear handle in the middle position. This isolates the landing gear actuators. Then fly around and wait until main air pressure builds back to 50 ATMOS. Select DOWN on the main gear handle again and see if the light comes on. If it does not, then use Emergency Air PROCEDURES. If it still does not come down, close the emergency air valve, fly around until the pressure builds back up on the emergency bottle and then TRY EMERGENCY PROCEDURES AGAIN! Note: Yak-50 pressurizes BOTH main and emergency bottles from the engine compressor, unlike the 52.
People looking at the gear cannot tell if it is really locked when you are flying, only that it "looks down". It would take a real YAK-50 expert to carefully see the angle of that gear to even make an educated guess. Chevron seal failure in the actuators is common. If you were to raise the gear at this point, what little is left can turn into slush or pieces and then you are looking at a gear up landing. Bottom line, yes, you should have used the emergency air procedures (read them carefully). If even THAT fails, having the gear handle in the middle, close the emergency air bottle valve, fly around and BOTH bottles will re-pressurize. Try the emergency procedure again! I'd keep doing that until I almost ran out of gas.
Good job on the "bounce" on the runway. The only reason it worked was that there was still air in the system pushing on that actuator. With a total chevron seal failure, it would not have.
Mark
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McFly
Joined: 21 May 2012
Posts: 101
Location: Scottsdale, AZ
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| Posted: Wed Jul 22, 2015 3:01 pm Post subject: YAK-50 landing gear actuators overhaul time. |
|
|
Thanks Jan.
Once I have it I will scan it and post it online for all Yak 50 guys to have access. I have been looking for one for 2 yrs.
Todd McCutchan
T-34A & Yak-50
Cell: (260) 402-1740
E-mail: todd(at)fastaircraft.com
www.fastaircraft.com
[quote] On Jul 22, 2015, at 1:28 PM, Jan Mevis <jan.mevis(at)informavia.be> wrote:
Hi Todd,
I'll try to make some copies, but it's an old book, so it'll take some time.
Jan
From: <owner-yak-list-server(at)matronics.com> on behalf of Todd McCutchan <todd(at)fastaircraft.com>
Reply-To: "yak-list(at)matronics.com" <yak-list(at)matronics.com>
Date: Wednesday 22 July 2015 17:35
To: "yak-list(at)matronics.com" <yak-list(at)matronics.com>
Subject: Re: YAK-50 landing gear actuators overhaul time.
Jan,
I would love to get a copy of that MX manual.
Please email me directly. The info is below.
Todd McCutchan
T-34A & Yak-50
Cell: (260) 402-1740
E-mail: todd(at)fastaircraft.com
www.fastaircraft.com
> On Jul 22, 2015, at 9:32 AM, Jan Mevis <jan.mevis(at)informavia.be> wrote:
>
>
>
> No, testing is no issue, but with air from the emergency system we don't
> let it go the whole way.
> I would be very scared doing that with the plane on jacks. The odds are
> that it would jump off the jacks.
> The one time that I had to use the emergency system in flight, I remember
> that it was a very violent experience.
> Impossible to not notice it, the gear gets slammed down with so much force
> and the whole plane shaked.
>
> The Lithuanian mechanic that services my Yak 50 does check the emergency
> system at each annual but he cuts the air supply before it's fully
> developped.
> Anyway, the Russian DOSAAF manual says that the main gear of the 50 should
> be rebuilt after 3 uses of the emergency system.
> Not only the actuators, the whole gear.
>
> We sometimes forget that the scheduled lifetime of the Yak 50 was rather
> short. The 50 was easily destined to be scrapped after certain mishaps.
>
> Of course we do test the normal system each year and then we do have the
> gear retract and extend several times, the whole way.
> That's no problem.
> We also do check the bottles each year.
>
> BR,
>
> Jan
>
>
> On 22/07/15 14:05, "George S. Coy" <owner-yak-list-server(at)matronics.com on
> behalf of george.coy(at)gmail.com> wrote:
>
>>
>>
>> Hmmm, So when the emergency gear extension is tested at very annual
>> condition extension, then it gets rebuilt every third year? I guess most
>> of
>> us missed that memo.
>> George
>>
>> --
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_________________
Todd McCutchan
Fast Aircraft
T-34A - N134FA
KDVT Hangar 33-13
Cell - 260.402.1740
Email: todd@fastaircraft.com
Skype: tmccutchan
Web: www.fastaircraft.com & www.flyams.com |
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