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Mono gear collapse

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VE3LVO(at)rac.ca
Guest

Posted: Sun Feb 25, 2007 8:41 am Post subject: Mono gear collapse

I was saddened to hear of that event - especially on take-off.......... 

and, of course because I contemplate the same possibility.

Is there a spot in the gear-down structure where the insertion of a 

bar/lever/whatever mightr inhibit an over-centre travel on a bumpy take-off 

(one which I may see fairly often up north)?  It might also stop inadvertent 

gear-up on display stands.



Ferg Kyle

Europa A064 914 Classic

scrimm

Joined: 09 Jan 2006
Posts: 81
Location: Gilbert, SC SC99

Posted: Sun Feb 25, 2007 9:03 am Post subject: Mono gear collapse

Question...



When the gear collapsed, what was the position of the gear lever after the

collapse?  In the down or up position? 



Steve Crimm

N42AH

For Sale

www.stephenscott.com/Europa

--

_________________
Steve Crimm
N42AH

gcrowder2

Joined: 09 Jan 2006
Posts: 136
Location: Golden, Colorado USA

Posted: Sun Feb 25, 2007 9:35 am Post subject: Mono gear collapse

I thought all Europa monos have the little finger latch that I has to be 

lifted first before

retracting the undercarraige.  The latch fits in a little slot that stops 

any movement

of the retraction lever.  Maybe the original builder added this as a mod but 

it works

great for me!  Very easy to use.



                                                Glenn

 	  Quote: 	
		  From: "Fergus Kyle" <VE3LVO(at)rac.ca>

Reply-To: europa-list(at)matronics.com

To: "EUROPALIST" <europa-list(at)matronics.com>

Subject: Mono gear collapse

Date: Sun, 25 Feb 2007 11:40:03 -0500






I was saddened to hear of that event - especially on take-off.......... 

and, of course because I contemplate the same possibility.

Is there a spot in the gear-down structure where the insertion of a 

bar/lever/whatever mightr inhibit an over-centre travel on a bumpy take-off 

(one which I may see fairly often up north)?  It might also stop 

inadvertent gear-up on display stands.



Ferg Kyle

Europa A064 914 Classic


	


_________________________________________________________________

Find a local pizza place, movie theater, and more….then map the best route! 

http://maps.live.com/?icid=hmtag1&FORM=MGAC01

Paul Boulet

Joined: 09 Jan 2006
Posts: 57
Location: Malibu, California

Posted: Sun Feb 25, 2007 9:58 am Post subject: Mono gear collapse

The gear lever was down and locked.  My collapse occured after landing roll out at about 5 kts ground speed.  A slight bump caused it to bounce off center and totally distort/destroy the gear lever and all the mechanisms attached to it.  The build manual is wrong and if it had been correct this never would have happened.



I'm surmising most of this because the accident occured with my test pilot at the controls.  Also I did not perform the teardown/rebuild converstion to tri gear- my builder assist center performed this.



Words to the wise.... take a look at someone else's mono gear retraction mechanism before accepting the manual's instructions as the gospel truth.



Paul Boulet N914PB



---

ami(at)mcfadyean.freeserv
Guest

Posted: Sun Feb 25, 2007 12:15 pm Post subject: Mono gear collapse

The problem with kit aircraft is that you have to  'reverse engineer' the manual to try to understand what the designer intended,  and then check that the components received come close. 

 A set of engineering drawings/plans would make it  all so much easier!

  

 Duncan McF.

 [quote]   ---

gcsmith(at)flyer.co.uk
Guest

Posted: Sun Feb 25, 2007 1:26 pm Post subject: Mono gear collapse

Answer.... That all depends on what you mean by "when the gear collapsed..."

it was a process that occupied a period of time, albeit a short one. Up

until the point that the aircraft came back down to earth after the surge

over the ski jump, the gear lever was in the down and locked position. When

the wheel hit the ground again (with the overcentre lock now in an

undercentre position) and the full weight of the aircraft was applied to the

LG12 lever, the mod 51 strut, the down gate etc etc, the lever took a bit

less than a blink of an eye to move to the "gear up" position -- I'm glad I

didn't have my hand in the way it would have been amputated. Since there is

no "up stop" on the Europa mono landing gear, the wheel was thrust up to the

top of the wheelwell where it wore all the paint off the flap lever and

ground away the bottom of the throttle box, filling the cockpit with nasty

smelling black smoke.



I presume that the point of your question is along the lines of why didn't

the little toggle lock or the LG12 lever or the down gate or whatever, stop

the gear from retracting, but be aware -- all that stuff in the cockpit is

there to stop you inadvertently retracting the gear, e.g. by bumping it with

your hand, there is no way that any of that stuff can take the undercarriage

loads -- they must be taken by the landing gear frame and that only happens

if the gear is 'overcentre'.



I know that the LG12 was securely in the downgate, and that the little

toggle lock was down when the aircraft hit the ground again, because it was

all damaged by the impact. When the overcentre gave way, the full

undercarriage loading was borne by the LG12 lever (but only for a VERY short

time) -- the LG12 was bent, the mod51 strut is now about 1cm shorter than

before and the lever guide plate, into which the slot and the downgate are

cut, was prised from the top of the tunnel. Believe me, if the gear is not

locked over centre everything goes belly up (literally).



Regards,

Graeme

  



--

gcsmith(at)flyer.co.uk
Guest

Posted: Sun Feb 25, 2007 1:31 pm Post subject: Mono gear collapse

Fergus,



I've tried to think of all kinds of safety mechanisms, I've come to the

conclusion that the only hope is to increase the degree of overcentre

locking and to ensure that when the LG12 is in the downgate, the LG08s are

jammed hard against the stops and there is no play anywhere to allow the

overcentre to be 'tripped' by a severe unloading of the suspension such as

would have happened when my aircraft surged over that bump. When it first

hit the bump, the suspension would have been fully compressed, then when the

wheel left the ground the suspension would have been very suddenly unloaded

and would have snapped back so fast that it must have tripped the overcentre

lock. Then when the wheel hit the ground again with the full weight of the

aircraft (plus g forces), there was nothing there to take the load except

the LG12 lever and the downgate in the cockpit ... Game over!



Graeme



 



--

gcsmith(at)flyer.co.uk
Guest

Posted: Sun Feb 25, 2007 1:36 pm Post subject: Mono gear collapse

Glenn,



My little finger latch works great as well, but don't misunderstand its

purpose. It is there to stop you accidentally retracting the gear, it is not

able to take the full landing loads  of the aircraft. If your overcentre

locking is not working, that little finger latch won't save you, see

explanation in replies to other posts on this subject.



Regards,

Graeme



--

hurstkr(at)redzone.com.au
Guest

Posted: Sun Feb 25, 2007 4:54 pm Post subject: Mono gear collapse

> Words to the wise.... take a look at someone  else's mono gear retraction mechanism before accepting the manual's instructions  as the gospel truth.



Paul,

  

 Specifically, what are the instructions to which you refer in the manual  ?  You've lost me at the moment.

  

 Regards

 Kingsley in Oz

    [quote][b]

ward.t(at)xtra.co.nz
Guest

Posted: Sun Feb 25, 2007 5:03 pm Post subject: Mono gear collapse

It was always interesting to note the company requiring a minimum 2 cm clearance between the top of the wheel and the fuselage line with the gear down. After installing the undercarriage  and then the weight of the engine etc my clearance is below the 2cm. However on reading the over centre problem and undercarriage coming up after a bump on T/O I would summise that perhaps the 2cm clearance requirement should not be stated. To remain in the over centre safe position (u/c down) the clearance is irrelevant and maybe why builders have taken it into account and therefore the undercarriage is too close to the over centre neutral position needing only a bump to reverse it.

Just a thought.

I had my u/c come up for a different reason, the rebate lock moved up after a bumpy landing allowing the lever to move IN SLOW MOTION up. The remedy is a $2 piano wire fix to spring load the latch in the down position. I have the details of that installation if anyone wants it. Could save you some money!!!

Tim

--

Tim Ward

12 Waiwetu Street

Fendalton

Christchurch.

Ph. 64 33515166

MOB 0210640221

ward.t(at)xtra.co.nz



---- Duncan & Ami McFadyean <ami(at)mcfadyean.freeserve.co.uk> wrote: 

[quote] The problem with kit aircraft is that you have to 'reverse engineer' the manual to try to understand what the designer intended, and then check that the components received come close. 

 A set of engineering drawings/plans would make it all so much easier!

 

 Duncan McF.

   ---

VE3LVO(at)rac.ca
Guest

Posted: Mon Feb 26, 2007 11:32 am Post subject: Mono gear collapse

Graeme,

        Thanks for the clarifications - much as I surmised - the lowering

mechanism won't stop an overcentre interruption, or a collapse.

        This brings me back to my original question:   That there may be a

structural intervention which IS strong enough to inhibit collapse. Perhaps 

insertion of a simple hydraulic cylinder? Of course this means a second (or 

more) action to prepare for landing but I don't mind the extra work! The 

distance-twixt-rubber-bumper-ends is intriguing..............

Ferg Kyle

Europa A064 914 Classic

josok-e(at)ukolo.fi
Guest

Posted: Mon Feb 26, 2007 1:05 pm Post subject: Mono gear collapse

Hi All,

It's a bit of a teaser, this thread about collapsing gear. Let me try my view on this. The gear is per desgn over-center. It's ever so little, and i did not really believe it. I moved the crates which supported the fuselage in the workshop a bit aside, so that they were only balancing the act, and it was impossible to raise the wheel. Support back in place and up she went. So i was happy until this thread. Im my case there is no play on the lever in the down position so far. So it can't get out of over center eh? The i remembered the demonstation fligts, the gear comes up easy, almost jumps up, until halfway, when pressure has to be applied. So it's the pressure on the flaps that will, on a bumpy take off or landing, pull happely out-of-over-center. That is, if there is any play in the system, more then the over center distance. Right? 



Kind Regards,



Jos Okhuijsen

Visit -  www.EuropaOwners.org

grahamsingleton(at)btinte
Guest

Posted: Wed Feb 28, 2007 1:41 pm Post subject: Mono gear collapse

Jos

the pressure on the flaps doen't cause any tendency to retract, it acts 

straight up the support brackets and through the pivot bolts. In flight 

you should be able to put the flaps anywhere from nearly down to nearly 

up and they will stay put. The only force on the lever is from the shock 

chord or your hand.

Graham



josok wrote:

 	  Quote: 	
		   

 

 Hi All,

 It's a bit of a teaser, this thread about collapsing gear. Let me try my view on this. The gear is per desgn over-center. It's ever so little, and i did not really believe it. I moved the crates which supported the fuselage in the workshop a bit aside, so that they were only balancing the act, and it was impossible to raise the wheel. Support back in place and up she went. So i was happy until this thread. Im my case there is no play on the lever in the down position so far. So it can't get out of over center eh? The i remembered the demonstation fligts, the gear comes up easy, almost jumps up, until halfway, when pressure has to be applied. So it's the pressure on the flaps that will, on a bumpy take off or landing, pull happely out-of-over-center. That is, if there is any play in the system, more then the over center distance. Right? 

 

 Kind Regards,

 

 Jos Okhuijsen

Graham Singleton
	




Tel: +441629820187

Mob: +447739582005

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