Today's Message Index:
----------------------
1. 05:05 AM - Re: Allegro 2000, 912UL Initial Engine Test Run (Hugh McKay III)
2. 06:27 AM - Re: Allegro 2000, 912UL Initial Engine Test Run (Thom Riddle)
3. 06:45 AM - Re: Allegro 2000, 912UL Initial Engine Test Run (Jean-Paul Roy)
4. 08:34 AM - Re: Allegro 2000, 912UL Initial Engine Test Run (Gilles Thesee)
5. 11:43 AM - Re: Allegro 2000, 912UL Initial Engine Test Run (Hugh McKay III)
6. 01:00 PM - Re: Allegro 2000, 912UL Initial Engine Test Run (Gilles Thesee)
7. 07:53 PM - Re: Allegro 2000, 912UL Initial Engine Test Run (Hugh McKay III)
Message 1
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| Subject: | Allegro 2000, 912UL Initial Engine Test Run |
--> RotaxEngines-List message posted by: "Hugh McKay III" <hgmckay@bellsouth.net>
Gilles: The times stated in my email are excessive. After reviewing the
actual sequence of events I shut down the engine after the CHT was
approaching 130 degrees C. It took about 15 min to reach the 130 degrees. I
did not hold the engine at 130 degrees for any length of time. I believe the
problem was that I was not moving (static) and the ambient temp. was about
88 degrees F. The air flow across the engine was only what the cowling
allowed. Has any one else experienced this high CHT while sitting on the
ground with the engine running for about 15 min.?
Hugh
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com]On Behalf Of Gilles
Thesee
Sent: Saturday, September 02, 2006 6:11 PM
Subject: Re: RotaxEngines-List: Allegro 2000, 912UL Initial Engine Test Run
--> RotaxEngines-List message posted by: Gilles Thesee
<Gilles.Thesee@ac-grenoble.fr>
Hi Hugh,
> Gentlemen: Today I ran my Rotax 912UL for its first test run.....
>
> 1. Started engine (engine started immediately).
> 2. Held engine rpm at 1000 for 5 min.
> 3. Oil pressure went to 5 bar on start.
> 4. After 5 min increased rpm to 2500
> 5. At 2500 rpm, oil pressure 4.0 bar, oil temp. 60 degrees C,
> cylinder head temp. 100 degrees C, fuel pressure 0.3 bar (held
> this rpm for 10 to 15 min.) I noticed the cylinder head temp
> gradually continued to rise.
>
I would have shut down long before that.
> 1. After 15 min gradually increased rpm to 4000
> 2. At 4000 rpm; Oil pressure 4.0 bar, oil temp. increased to 120
> degrees C, cylinder head temp increased to 130 degrees C, fuel
> pressure 0.3 bar (held this rpm for another 15 +/- min.)
> 3. At 4000 rpm checked both ignition (kill) switches. rpm drop was
> aprx. 100 rpm on each switch.
> 4. At this point the engine had been running for about 30 to 40
> minutes sitting on the ground with the cowling on and the
> ambient temp. at aprx.88 degrees F.
> 5. I then increased the engine speed to max throttle position and
> checked the engine rpm. Max rpm was 4600 rpm. Held this speed
> for one minute. Based on this number the existing Prop pitch
> (17.5 degrees by the Warp Drive Protractor) needs adjusting to
> get the rpm up to the 4800-5100 range. I assume I will have to
> reduce the pitch to do this (i.e. less pitch equals higher rpm).
> How much less than 17.5 degrees I don't know. I'm guessing about
> 1 to 1.5 degrees.
> 6. At max throttle, 4600 rpm; oil pressure 3.4 bar, oil temp. 120
> degrees C, cylinder head temp 130 degrees C and rising, fuel
> pressure 0.3 bar.
> 7. Reduced engine speed to 1000 rpm for 3 min. for cool down.
>
IMHO, 40 minutes on the ground seems quite an ordeal for a first engine
run. Especially with the temperatures you achieved. 130C seems to me
way too high.
One thing common to any piston engine, is they need to be treated with
care at the beginning of their operating life. And you don't want to
thermally load them during the run in period.
If it were my engine, I'd do short runs progressively increased in RPM
and duration, with a careful monitoring of temperatures. And I would
stop as soon as they climb too high. Adequate airflow is key.
When building a 4-seater project, I conducted a thorough cooling
investigation, and designed a radiator duct which performs very well,
with great ease of adjustment.
See :
http://contrails.free.fr/engine_refroid.php
http://contrails.free.fr/tunnel_en.php
>
> 1.
>
>
> Note: After engine shut down coolant in over flow bottle was boiling,
> and there was evidence of overflow on the asphalt.
>
This is no surprise.
First start, run 30 seconds, shut down, check everything.
Then resart for a few minutes, without allowing the temps to exceed the
lower authorized range, shut down, check, etc...
> I noticed that the specs on the Texaco Anti-freeze coolant container
> showed that for a 50/50 mix ratio and a 15 psi radiator cap (my cap is
> rated 1.2 bar or 17.2 psi), the boil over protection is only 129.3
> degree C. For a 60/40 mix ratio the protection goes up only to 132.2
> degrees C. This is the max. recommended mix ratio. If the CHT gauge is
> correct I exceeded the boil over protection for the mixture.
>
It's not the boiling that harms the engine, but high CHT. To the
contrary, boiling helps reducing temps, that is as long as there is
coolant to boil, and not for 40 minutes. You definitely need cooling
airflow to correctly reject heat from the engine.
>
> The Rotax Engine Operators Manual 10.2.1 states that the ratio of
> anti-freeze to water should be increased if boiling should occur. I
> can only go to a 60/40 and that only protects to 132.2 degrees C.
>
> One thing that concerned me when I filled the engine cooling system,
> it took less than one gallon (aprx. 3 quarts) of 50/50 mix to fill the
> system. This seems to me to be a very small amount of liquid to cool
> the engine properly. What is the proper volume of coolant in the
> Allegro 2000 cooling system?
>
> Everything seemed to be normal except the CHT. Can any one help me
> with this problem?
>
The Rotax 91X series are very enduring engines, so you may hope you did
not really damage your engine.
I would suggest you start again the right way :
- Download the applicable cooling SBs and service letters from the Rotax
website and read them thoroughly.
- Seek the advice of a knowledgeable Rotax mechanic, engineer or dealer.
- Check for adequate engine and radiator installation.
- Do not do long ground runs with no cooling.
Best of luck,
Regards,
Gilles Thesee
Grenoble, France
http://contrails.free.fr
Message 2
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| Subject: | Re: Allegro 2000, 912UL Initial Engine Test Run |
Hugh,
Though they do have a very explicit run-in procedure for their 2-stroke
engines, Rotax does not require a run-in sequence for the 912 series
engines. Maintaining all parameters within normal ranges is important
though, especially while the engine is new. You allowed the oil
temperature to get above the normal range (90-110C) but kept it below
the max of 140C so I would not be too concerned about that. There is no
normal range specified for the CHT and you kept it below the 150C max.
Again no real concern. Oil pressure was maintained in normal range. No
concern there either. Note the temperature limits are different for the
912ULS engines.
Your report was very thorough with the exception of what the
temperatures were when you shut down the engine. You stated that you
let the engine cool down for 3 minutes but did not mention what the
temps were when you shut it down. In normal operation of our Allegro
2000 912UL, the engine has had plenty time to cool off for shutdown
after final approach and landing at idle, taxiing off the runway and
taxiing to hangar. If you don't let the engine cool down properly, then
the overflow coolant at ambient pressure would be expected to boil. On
static runs I would do the cool down at 2,000 rpm until the oil
temperature dropped into the low end of normal range before shutting
down. As I said, in normal operations, we've never had to let ours cool
down after taxiing to the hangar.
Rotax recommends letting the engine cool down at 2,000 rpm before
shutting it down, not 1,000 rpm. 1,000 rpm is too slow for this engine
and idle should be set to 1400 rpm minimum to 1800 max. Note that the
idle speed must be set when the engine is at normal operating
temperatures. If done at cooler temps, it will change when warmed up to
normal temps. Extended idling at too low rpm on the 912 can cause
gearbox damage. Since the Allegro glides so well, you will find that
setting the idle at the low end of the 1400-1800 rpm range is best. If
you set it at the high range, you will have trouble keeping the
airspeeds down on final approach.
We have not changed our coolant yet so I don't know what the total
system capacity is, but I suspect it is not very much. Remember, this
is not a big engine (1.2 liters) and the cooling system is pretty
compact.
I would decrease the prop pitch by no more than 1 degree for first
change. You may be surprised how much rpm difference 1/2 degree can
make. The range you are looking for (4800-5100 rpm) static is good for
the Allegro. Ours runs about 4900 rpm static and yields best cruise
speeds at this pitch. 5100 rpm static would give better climb.
Thom Riddle
FAA Powerplant Mechanic
Allegro 2000 #03-202
Message 3
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| Subject: | Re: Allegro 2000, 912UL Initial Engine Test Run |
These are very good informations. Thanks Thom for posting them.
Jean-Paul
do not archive
----- Original Message -----
From: Thom Riddle
To: rotaxengines-list@matronics.com
Sent: Sunday, September 03, 2006 9:25 AM
Subject: Re: RotaxEngines-List: Allegro 2000, 912UL Initial Engine
Test Run
Hugh,
Though they do have a very explicit run-in procedure for their
2-stroke engines, Rotax does not require a run-in sequence for the 912
series engines. Maintaining all parameters within normal ranges is
important though, especially while the engine is new. You allowed the
oil temperature to get above the normal range (90-110C) but kept it
below the max of 140C so I would not be too concerned about that. There
is no normal range specified for the CHT and you kept it below the 150C
max. Again no real concern. Oil pressure was maintained in normal range.
No concern there either. Note the temperature limits are different for
the 912ULS engines.
Your report was very thorough with the exception of what the
temperatures were when you shut down the engine. You stated that you let
the engine cool down for 3 minutes but did not mention what the temps
were when you shut it down. In normal operation of our Allegro 2000
912UL, the engine has had plenty time to cool off for shutdown after
final approach and landing at idle, taxiing off the runway and taxiing
to hangar. If you don't let the engine cool down properly, then the
overflow coolant at ambient pressure would be expected to boil. On
static runs I would do the cool down at 2,000 rpm until the oil
temperature dropped into the low end of normal range before shutting
down. As I said, in normal operations, we've never had to let ours cool
down after taxiing to the hangar.
Rotax recommends letting the engine cool down at 2,000 rpm before
shutting it down, not 1,000 rpm. 1,000 rpm is too slow for this engine
and idle should be set to 1400 rpm minimum to 1800 max. Note that the
idle speed must be set when the engine is at normal operating
temperatures. If done at cooler temps, it will change when warmed up to
normal temps. Extended idling at too low rpm on the 912 can cause
gearbox damage. Since the Allegro glides so well, you will find that
setting the idle at the low end of the 1400-1800 rpm range is best. If
you set it at the high range, you will have trouble keeping the
airspeeds down on final approach.
We have not changed our coolant yet so I don't know what the total
system capacity is, but I suspect it is not very much. Remember, this is
not a big engine (1.2 liters) and the cooling system is pretty compact.
I would decrease the prop pitch by no more than 1 degree for first
change. You may be surprised how much rpm difference 1/2 degree can
make. The range you are looking for (4800-5100 rpm) static is good for
the Allegro. Ours runs about 4900 rpm static and yields best cruise
speeds at this pitch. 5100 rpm static would give better climb.
Thom Riddle
FAA Powerplant Mechanic
Allegro 2000 #03-202
http://www.matronics.com/Navigator?RotaxEngines-List
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http://wiki.matronics.com
Message 4
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| Subject: | Re: Allegro 2000, 912UL Initial Engine Test Run |
--> RotaxEngines-List message posted by: Gilles Thesee <Gilles.Thesee@ac-grenoble.fr>
Hugh and Thom,
The following update re cooling may be of interest.
>
> There is no normal range specified for the CHT and you kept it below
> the 150C max.
Rotax 912 operator's manual does specifiy a normal CHT range of
75-110C with a red mark at 135C/150C for the hottest cylinder (to be
determined by tests) IF you switch to Evans water-free coolant.
If you stick to the 50/50 coolant, your CHT redlines is 120C with the
1.2 bar cap and only 115C with the old 0.9 bar cap.
The normal oil temp range is 90-110C.
I would strongly advise you to download and read the last applicable
Rotax recommendations. Rotax runs a free subscription service to advise
you of Service Bulletins, Service Letters and manual updates. You can
also search their website by engine s/n.
Regarding engine run-in, the Rotax takes about 20-35 hours to run-in, as
indicated by the lower running temperatures attained after the initial
period. Of course, it is not i"n the manual", but to achieve optimal
life for a new engine, it is best not to thermally abuse it during the
bedding down process. Prolonged ground runs are best avoided.
BTW, Philip Lockwood has written interesting articles on the
installation and operation of the Rotax 4-strokes.
FWIW,
Best regards,
Gilles
http://contrails.free.fr
Message 5
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| Subject: | Allegro 2000, 912UL Initial Engine Test Run |
--> RotaxEngines-List message posted by: "Hugh McKay III" <hgmckay@bellsouth.net>
Thom/Gilles:
I have read the FAA Special Airworthiness Information Bulletin dated Aug.
30, 2005 and the Austro Control AD No. A-2004-004R1 dated December 22, 2004,
both of which address this issue. The FAA document simply states that
operating above the 120 degree F with 50/50 mix, loss of coolant and engine
over heating can occur. That did occur. The Austro Control AD states that
the Max CHT is 120 degrees F with 50/50 mix. I exceeded that (130 degrees
F). All that being said, my question is "have I damaged my engine"? Any
thoughts?
Hugh
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com]On Behalf Of Gilles
Thesee
Sent: Sunday, September 03, 2006 10:33 AM
Subject: Re: RotaxEngines-List: Allegro 2000, 912UL Initial Engine Test Run
--> RotaxEngines-List message posted by: Gilles Thesee
<Gilles.Thesee@ac-grenoble.fr>
Hugh and Thom,
The following update re cooling may be of interest.
>
> There is no normal range specified for the CHT and you kept it below
> the 150C max.
Rotax 912 operator's manual does specifiy a normal CHT range of
75-110C with a red mark at 135C/150C for the hottest cylinder (to be
determined by tests) IF you switch to Evans water-free coolant.
If you stick to the 50/50 coolant, your CHT redlines is 120C with the
1.2 bar cap and only 115C with the old 0.9 bar cap.
The normal oil temp range is 90-110C.
I would strongly advise you to download and read the last applicable
Rotax recommendations. Rotax runs a free subscription service to advise
you of Service Bulletins, Service Letters and manual updates. You can
also search their website by engine s/n.
Regarding engine run-in, the Rotax takes about 20-35 hours to run-in, as
indicated by the lower running temperatures attained after the initial
period. Of course, it is not i"n the manual", but to achieve optimal
life for a new engine, it is best not to thermally abuse it during the
bedding down process. Prolonged ground runs are best avoided.
BTW, Philip Lockwood has written interesting articles on the
installation and operation of the Rotax 4-strokes.
FWIW,
Best regards,
Gilles
http://contrails.free.fr
Message 6
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| Subject: | Re: Allegro 2000, 912UL Initial Engine Test Run |
--> RotaxEngines-List message posted by: Gilles Thesee <Gilles.Thesee@ac-grenoble.fr>
Hugh,
> I have read the FAA Special Airworthiness Information Bulletin dated Aug.
> 30, 2005 and the Austro Control AD No. A-2004-004R1 dated December 22, 2004,
> both of which address this issue. The FAA document simply states that
> operating above the 120 degree F with 50/50 mix, loss of coolant and engine
> over heating can occur. That did occur. The Austro Control AD states that
> the Max CHT is 120 degrees F with 50/50 mix.
Thoroughly reading the Maintenance, Installation and Operator's manuals,
and the SBs and SLs direct from Rotax will give you a better
understanding of the engine operation and limitations.
> I exceeded that (130 degrees
> F). All that being said, my question is "have I damaged my engine"?
>
Only the engine knows ;-(
You sure did not do it much good, but did you do much harm ? Only a
knowledgeable Rotax engineer, with much experience about this type of
engine could answer. Why not give Lockwood Aviation a call ?
What I would advise you not to do again, is remove the coolant cap
before the engine has cooled down. The circuit is pressurized, and by
premature release of the pressure, the coolant starts to boil. And
boiling means massive cooling. That is shock cooling the hot spots
within, and no engine likes that.
But those engines are very rugged, and very tolerant. So Lockwood may
shrug about it. (and you risk scalds).
Out of memory, the maintenance or operator manual may give information
about the checks following overheating.
What I would do after consulting knowledgeable people :
After those checks, start again, and limit ground operation to what is
necessary to ascertain correct operation. During flight tests, limit
full throttle operation to what is necessary to climb to a safe
altitude, without leaving the temperatures exceed the normal operating
range. During descent, beware of shock-cooling.
For subsequent flights, never let the engine run outside its
limitations, and gradually increase cruise power duration, with, at the
beginning, short bursts at full throttle.
Best regards,
Gilles
http://contrails.free.fr
Message 7
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| Subject: | Allegro 2000, 912UL Initial Engine Test Run |
--> RotaxEngines-List message posted by: "Hugh McKay III" <hgmckay@bellsouth.net>
Gilles:
Thanks for the advice and counsel. I will call Lockwood Aviation. By the
way, I did not open the coolant cap until the engine had cooled down. The
boiling coolant was in the overflow bottle with some being dumped out
through the overflow line. After cool down, the coolant that was in the
overflow bottle was sucked back into the engine. I then opened the cap and
replenished the lost coolant (aprx. 1 pint).
Hugh
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com]On Behalf Of Gilles
Thesee
Sent: Sunday, September 03, 2006 2:58 PM
Subject: Re: RotaxEngines-List: Allegro 2000, 912UL Initial Engine Test Run
--> RotaxEngines-List message posted by: Gilles Thesee
<Gilles.Thesee@ac-grenoble.fr>
Hugh,
> I have read the FAA Special Airworthiness Information Bulletin dated Aug.
> 30, 2005 and the Austro Control AD No. A-2004-004R1 dated December 22,
2004,
> both of which address this issue. The FAA document simply states that
> operating above the 120 degree F with 50/50 mix, loss of coolant and
engine
> over heating can occur. That did occur. The Austro Control AD states that
> the Max CHT is 120 degrees F with 50/50 mix.
Thoroughly reading the Maintenance, Installation and Operator's manuals,
and the SBs and SLs direct from Rotax will give you a better
understanding of the engine operation and limitations.
> I exceeded that (130 degrees
> F). All that being said, my question is "have I damaged my engine"?
>
Only the engine knows ;-(
You sure did not do it much good, but did you do much harm ? Only a
knowledgeable Rotax engineer, with much experience about this type of
engine could answer. Why not give Lockwood Aviation a call ?
What I would advise you not to do again, is remove the coolant cap
before the engine has cooled down. The circuit is pressurized, and by
premature release of the pressure, the coolant starts to boil. And
boiling means massive cooling. That is shock cooling the hot spots
within, and no engine likes that.
But those engines are very rugged, and very tolerant. So Lockwood may
shrug about it. (and you risk scalds).
Out of memory, the maintenance or operator manual may give information
about the checks following overheating.
What I would do after consulting knowledgeable people :
After those checks, start again, and limit ground operation to what is
necessary to ascertain correct operation. During flight tests, limit
full throttle operation to what is necessary to climb to a safe
altitude, without leaving the temperatures exceed the normal operating
range. During descent, beware of shock-cooling.
For subsequent flights, never let the engine run outside its
limitations, and gradually increase cruise power duration, with, at the
beginning, short bursts at full throttle.
Best regards,
Gilles
http://contrails.free.fr
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