REFLECTOR: Retractable Gear Issue--- long story

Sun Sep 28 13:46:44 CDT 2014

Hello Jack,
Happy the story had a happy ending.
Some observations and recommendations -
* For the next few flights bring along a long, heavy stick to "whack" 
the main landing gear into its down-and-locked position!
* Regarding the free fall of the landing gear ... I am curious why both 
the main and nose linkage failed to extend to the down and locked 
position.  During free fall tests (on jacks) the gear should fall down 
with authority and within 5-seconds.  Typically the nose gear doors open 
first, the nose gear falls to maybe 80% of its stroke, then the mains 
fall under gravity force until they travel into the down and locked 
position, and then (finally) the nose gear free falls to its down and 
locked position.  Lubrication of all pivot and linkage friction points 
is recommended.  The nose gear gas spring should be replaced if it is 
not delivering full force (if over 1-year old, suggest replacing gas 
spring, regardless of service cycles).  The main gear pivot bolt lock 
nuts need NOT be tight.  Freedom of the main gear to pivot is a must! 
Review the installation of the main gear linkage.  Are recommended 
washers in place?  Truly, this should NOT be a 'slow motion' free fall 
event.  Loosen bolts and lubricate as necessary to obtain freedom of 
movement.
Let us know what you discover!
Best,
Scott B.
www.sierrabravoaircraft.com

On 9/28/2014 2:26 PM, Jack Prock via Reflector wrote:
>
> HI,
>
> So I have been doing test flying of my new XL-RG and I was having an 
> issue with the oil not cooling. Turned out the Vernatherm was not 
> closing completely. Made every flight under 15 minutes, which was 
> frustrating. Anyway, this morning I went out to test my latest change 
> to see if the oil temp would stabilize. So within 15 minutes it was 
> steady at 220… YEA! It was nice to not be able to fly and not worry 
> about that.
>
> So after 20 minutes, oil temp steady, I decided to raise the landing 
> gear. Mind you, I had raised and lowered the gear probably 40 or 50 
> times over the past 8 years, and every time they came up and went down 
> perfectly. I had also made sure that the wheel wells had clearance, 
> since a friend had that issue in his Velo. So they came up great, I 
> was sitting fat, dumb and happy. I then went to lower them and they 
> lowered fine… or so I thought. I looked down and I had two yellow 
> lights on the rear gear. I looked back and they had lowered 90%, but 
> the over center arms had not locked. They were about 2 inches above 
> locking.
>
> I cycled them a half dozen more times, and every time the rear gear 
> would stop at the same point. I don’t have the rear cover panel on, so 
> I can easily see the gear arms. Man it was so frustrating to be 
> sitting there, be able to see them, and not crawl back there to push 
> them down the last two inches.
>
> So I flew around for a while and tried yanking on the yoke a bit to 
> see if I could get them to budge. Mind you I have about a total of 1 
> hour on the plane at this point, so I am still being very cautious 
> about any sudden movements of the control surfaces.
>
> Long story short I declared an emergency, and told somebody on the 
> ground to let 911 know there may be an issue with the gear. He got 
> them on the line but they didn’t send anyone out, since to the guy on 
> the ground it looked like the gear was down.
>
> Lincoln Ca is 6000+ feet long, so I had time to touch the gear on the 
> ground and try and get them to lock. And luckily, that is what 
> happened. I touched the left main, raised the plane up a few feet, and 
> I heard the gear lock. A quick look at the indicator lights and I had 
> 3 green. Landed uneventfully and felt very lucky this didn’t turn into 
> a very expensive flight.
>
> So now the question to the group. Does anyone grease the landing gear 
> bolts? Something is binding. Anyone have any experience with this? 
> There are 5 total joints in the rear gear landing mechanism and one of 
> them is binding when there is a rearward force being applied.
>
> I think the best way to test this moving forward is to lower the gear 
> with two people pulling ropes attached to the gear so that I can make 
> sure the gear isn’t binding with a rearward force.
>
> Anyone have any experience, guidance, snide comments?
>
> Jack
>
>
>
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