Today's Message Index:
----------------------
1. 06:10 AM - Re: ZK-TWU gear leg update (nicoCSS)
2. 06:31 AM - Re: ZK-TWU gear leg update (Stuart Hutchison)
3. 06:43 AM - Re: Rocket II gear collapse (Nancy and Randy)
Message 1
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| Subject: | ZK-TWU gear leg update |
Hi Jay,
How old is the airframe and could the climate in which it was primarily
operated be a factor? This doesn't look like an hour-based problem. One
may have to pull the under carriage apart every three years or so.
Just my thoughts.
Nico
From: owner-rocket-list-server@matronics.com
[mailto:owner-rocket-list-server@matronics.com] On Behalf Of Jay
McIntyre
Sent: Wednesday, August 20, 2014 8:15 PM
Subject: Rocket-List: ZK-TWU gear leg update
Hi all...
thanks for the various replies both on the list and off.
We received the aircraft in the shop this morning and I was surprised to
find that the leg had fractured clean off where it comes out of the tube
on the engine mount.
We have not had a chance to do any proper inspection as yet but it would
appear that there is no damage to the engine mount, firewall or any part
of the airframe other than paint damage on the RH wing tip.
It has been suggested it could be a case of hydrogen embrittlement - God
knows what you are meant to do to stop that in general maintenance terms
and what sort of inspections would stop that...
Attached are photos of the legs. LH leg is still in one peice but I
believe it is bent.
Hard to tell from the photo looking down the length of it, but the top
of the leg does not seem to be in the same longitudinal plane as the
rest of the gear leg - correct me if it is meant to be this way!
(We are replacing both legs regardless)
As you can see the smoking gun would appear to be the point where the
leg exits the bushing in the leg socket as it appears to have sheared
off where the shoulder has been created.
Question is, what does one do about it to stop re-occurrence? Airframe
has 1340 hours on it and I think the legs are the same age.
Regards, Jay
Message 2
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| Subject: | Re: ZK-TWU gear leg update |
What a great example of galling/spalling and stress risers !!!
All of a sudden I=92m very glad my stilts have #5 Morse tapers at the
top with a nut to torque periodically, which will stop the leg from work
hardening in their sockets!
Cheers, Stu
On 21 Aug 2014, at 11:09 pm, nicoCSS <nico@cybersuperstore.com> wrote:
> Hi Jay,
> How old is the airframe and could the climate in which it was
primarily operated be a factor? This doesn't look like an hour-based
problem. One may have to pull the under carriage apart every three
years or so.
> Just my thoughts.
> Nico
>
>
> From: owner-rocket-list-server@matronics.com
[mailto:owner-rocket-list-server@matronics.com] On Behalf Of Jay
McIntyre
> Sent: Wednesday, August 20, 2014 8:15 PM
> To: rocket-list@matronics.com
> Subject: Rocket-List: ZK-TWU gear leg update
>
> Hi all...
> thanks for the various replies both on the list and off.
> We received the aircraft in the shop this morning and I was surprised
to find that the leg had fractured clean off where it comes out of the
tube on the engine mount.
> We have not had a chance to do any proper inspection as yet but it
would appear that there is no damage to the engine mount, firewall or
any part of the airframe other than paint damage on the RH wing tip.
> It has been suggested it could be a case of hydrogen embrittlement -
God knows what you are meant to do to stop that in general maintenance
terms and what sort of inspections would stop that...
>
> Attached are photos of the legs. LH leg is still in one peice but I
believe it is bent.
> Hard to tell from the photo looking down the length of it, but the top
of the leg does not seem to be in the same longitudinal plane as the
rest of the gear leg - correct me if it is meant to be this way!
> (We are replacing both legs regardless)
>
> As you can see the smoking gun would appear to be the point where the
leg exits the bushing in the leg socket as it appears to have sheared
off where the shoulder has been created.
>
> Question is, what does one do about it to stop re-occurrence? Airframe
has 1340 hours on it and I think the legs are the same age.
>
> Regards, Jay
>
>
>
>
Message 3
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| Subject: | Re: Rocket II gear collapse |
Jay,
Just wanted to chime in here. I mounted a two-blade MT propeller
(MTV-15-B-C/C203-58) on my HR2 (IO-540-C4B5) about a year ago and have
had very good results. I shed about 15 pounds from the previous
(Hartzell) installation, including a lighter and smaller propeller
governor. That also resulted in a CG location a bit further aft (I
think most HR2s have a pretty forward CG, no?). Another byproduct was
the "aerobatic" prop governor which goes to "course" pitch in the event
of an oil pressure loss and reduces the chance of over speeding the
engine/prop during aerobatics (hammerheads/inverted flight). I have
been seeing about 180 knots true airspeed at 2200 rpm and 22 inches of
manifold pressure with just a touch over 12 gallons per hour fuel flow.
Good luck with the rebuild effort. Thanks for keeping the group
informed and I will definitely inspect my gear legs for any sign of
corrosion.
All the Best
Randy Sage
Peachtree City, Georgia
USA
----- Original Message -----
From: Jay McIntyre
To: rocket-list@matronics.com
Sent: Tuesday, August 19, 2014 6:06 AM
Subject: Rocket-List: Rocket II gear collapse
Hi all.
I look after the maintenance on a Rocket II (S/N 004, ex N67CW) down
here in New Zealand.
Unfortunately it suffered a collapse of the RH gear leg on Saturday
during take off on a grass strip.
The pilot/owner thinks he hit a small depression/hole during the T/O
roll which may have contributed to the final collapse.
The aircraft is most often operated from grass strips so it is perhaps
not a big surprise that a failure has occurred.
(Naturally we keep a close eye on the engine mount / U/c mount during
inspections but one can only see so much...)
I have not actually seen the damage yet as the aircraft is in transit
on a trailer but I imagine the leg socket has been ripped out of the
engine mount as opposed to the titanium leg fracturing. Airframe damage
appears to be minimal but we will see!
(Photos of the damage have not been clear enough to show what has
happened).
I am trying to get ahead of the game prior to the aircraft's arrival
at our facility by getting some information from the Rocket community as
follows:
1)Short of operating off sealed strips, is there an improved engine
mount that can be purchased / made that goes some way to preventing
reoccurring cracks etc in the mount?
2) Is any of the F1 Rocket componentry usable on the Harmon Rocket II?
eg the longer gear legs and engine mount.
3) Which prop should we go for? Engine is an IO-540B1C and the owners
primary concern is speed... I have read that the stock standard
Hartzell 2 blader is the best bet here?
Who is out there supplying bits that will best suit our needs and get
us flying again quickly?
Thanks in advance,
Jay
JEM Aviation Ltd
New Zealand
www.jemavation.co.nz
+64 3 578 3063
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