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CJ6 gear collapse in Ontario

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elmar.h(at)shaw.ca
Guest

Posted: Fri Jan 21, 2011 3:10 pm Post subject: CJ6 gear collapse in Ontario

last year there was an ugly gear

failure in Ontario/Canada.



The pilot posted some pictures on his

website, looks quite scary.



http://picasaweb.google.com/skidmk/FXMIPostAccident#



Unfortunately I have no information

how this happened, any ideas?



cheers



Elmar

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keithmckinley

Joined: 11 Aug 2008
Posts: 434

Posted: Fri Jan 21, 2011 5:44 pm Post subject: Re: CJ6 gear collapse in Ontario

I suggest you ask him, not vultures row.

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Vic

Joined: 12 Aug 2008
Posts: 116
Location: Southern Bavaria

Posted: Sat Jan 22, 2011 7:06 pm Post subject: Re: CJ6 gear collapse in Ontario

Servus Elmar,



judging from the pictures I guess this was a full-bore gears-up landing and I believe you´ve come to the same idea shown in your next posting on this forum. A real landing gear collapse is unlikely to inflict all three legs so damage would show either on the nose section or on one side of the plane. 

  There is a photo of an 18 T on the web with one main gear collapsed after landing. The published cause was a broken or loose screw on the piston in the gear actuator as seen in my photo on the left end. I took this photo last week after 4 years of use. During this period I never added any liquid into the pneumatic system but certainly drained it in the first minutes after each flight. Some effect from water condensation can be seen on the grease but there is definitely no other corrosion on the locking balls or the sturdy spring etc. which might endanger the function. I do believe - as some more do in this forum - that a good grease with max. viscosity base oil in it is the best bet for safe corrrosion protection. Any other thin oil or solvent for servicing the lines will wash the protection away. A type of clear grease used for motorcycle chains could be applied for rust protection and heavy grease for the locking mechanism. If you could find a grease which is very , very hard to wipe off your fingers - well, that´s the best for the job, NLGI class 4-5 .

  The pneumatic seals were lubricated with silicone grease and that was that for 4 years. Please take this warning : Don´t use WD 40 on sliding surfaces - after some time of drying this stuff forms a very sticky residue blocking any motion. Just apply some of it on a piece of tin and test it after some weeks, it will have transformed from oil to resin.

 Now there remains the question how to protect the lines ? I am tempted to separate all actuators and use chain spray for the lines. This leaves a sticky oily film great for rust protection. 

  Sorry for posting this last topic now, it should have been in a thread some time ago but I did not have hard facts then. But in some ways this is not quite off-topic regarding landing gear collapses. 

Cheers

Vic

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skidmk

Joined: 19 Nov 2007
Posts: 171
Location: Ottawa, Ontario

Posted: Mon Jan 24, 2011 7:25 am Post subject: Re: CJ6 gear collapse in Ontario

To Quell any supposition and or controversial, argumentative postings from the varia of subject matter experts we have here:

FXMI was completing its 4th night landing (of 5) for the pic's night rating re-currency.  FXMI departed CYRO and due to a low air condition, flew for approximately 20 minutes and then completed a touch and go at CYOW on a 10,000 foot runway.  Upon the touch and go, the pilot was heard to say on the frequency that there was a strange noise emmanating from the gear and that he was returning to CYRO.  



Upon landing at CYRO, the PIC  did not notice any strange noises coming from the landing gear this time.  The PIC usually used an ANR helmet for his flights, but this flight had been conducted with a non-anr Pilot Headset.  The Pic taxied around the airport at low speed trying to "hear" the strange gear noises again.  The PIC then concluded the noise may have been an anomaly, due to the normal noises the aircraft produced were usually "squelched" by the ANR.



The PIC, then taxied to position at CYRO and proceeded to complete another take off and landing.  Upon the normal landing and take off, the pilot exited the runway, taxied back along the taxiways to the threshold and departed again. Although, this time the pilot noticed a low air condition again (+/- 23atms).   The pilot did not, again, notice the strange sounds he had heard at CYOW.  The pilot during all landings checked for a 3 green condition, as well, when dark, this pilot uses his flashlight to insure the poles are visible.



 The aircraft landed normally, and slowed to a "fast taxi speed", the pilot initiated right rudder to exit into the taxiway and the right gear leg folded.  At this point the pilot's main concern became shutting down the engine, shutting off fuel and electrics.  While this was being done the aircraft continued under power, veered to the right whereupon it struck some runway lights.  The first runway light struck folded the nose gear. The second runway light was struck, and finally the left gear leg collapsed.  It is not clear if the geometry of one gear leg holding everything up and plus the runway light strike, and subsequent roll into the rough grass area caused the left gear to fold or not.



The aircraft came to rest in the grass area, and the pilot got out.  No injuries, and at first damage to the aircraft didn't look too serious.



This sequence of events was discribed to one of our Nanchang repair "Guru's" and it was felt that the downlock actuator may have failed, and coupled with a low air condition the other 2 gear legs may not have "locked" all the way.   Again, there were 3 green, and poles were visible.  In hindsight, in the dark, with only a flashlight to look at the poles, they may not have been "fully" up.

The aircraft was written off by the insurance company.  The "straw for the camels back" was a landing light nearly cut the rear spar on the center section in half.  Expensive fix.



I am the pilot, so I know what happened, there were witnesses, they saw what happened.  This was not a gear up landing.



Any other questions can be directed to me directly.



Mike

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_________________
Mike "Skidmk" Bourget
Ottawa, Ontario

elmar.h(at)shaw.ca
Guest

Posted: Mon Jan 24, 2011 3:45 pm Post subject: CJ6 gear collapse in Ontario

Hi Mike,



thank you very much for your very informative

posting.

I am very sorry having heard what happened

to your beautiful aircraft, the pictures

on your website look devastating.



The reason I am looking into gear related

accidents is that I believe there are some

ways to make the undercarriage operation on 

YAKs and CJs safer.



My personal nightmare is that I pull up

the gear accidentally while doing a 

touch and go or cleaning up the the plane 

at the hold line.



I am currently working on a squat-switch

solution for the CJ and I am waiting now

for better weather conditions to test it 

in real time conditions. If you are interested 

I will keep you posted.



Thanks again and good luck with your new

bird.



cheers



E.

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