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RV14A Nose Wheel Fairing Detachment on Landing

design4p

Active Member
Hi,

Has anyone had the same experience as me.

RV14 Nose Wheel Fairing Detachment on Landing.

I am in the process of flight testing covering the test schedules of the LAA (light Aircraft Association) in the UK and on landing after only 6 hours of flying the nose wheel fairing detached.

I have attached photos of the damage. I have re-assembled the parts with one layer of glass fibre on the fractured edges to try to establish the cause of the problem.

An idea is that the 8 countersunk screws are not sufficient to hold the Fairing to the Fairing Bracket. Also the large OD diameter of the washer within the Fork Nose axle bolt assembly (Washer 062 25783054) (Page 40A-07) the OD is too small.

Any suggestions of possible causes would be welcome.

Regards John
 

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No problems in 170 hours. I use tinnerman washers on all of the attachment screws and have more tire clearance than called for around the bottom too. Perhaps the tire (tyre) deformed enough on landing to catch the edge of the wheel pant and ripped it off the mounting? Are there cut marks on the tire?
 
The crack in the attach bracket would seem to indicate that the mid to upper left side of the fairing hit a stationary object. No issues with the screws would caused the attach bracket to crack like that. The scrape marks in the paint seem to reinforce that speculation. They are too straight and symmetrical to have been caused by the fairing bouncing around after separation.
 
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Grass or paved?

it would seem to me that the tire pressure may have been low enough to allow it to compress and the fairing hit the runway or something on the runway. Were you landing on a moist/soft field? Did you take any divits? How fast were you going when you set the nose wheel down?
 
Thank you for the replies so far

Yes - I will be using tinnerman washers or similar in my new nose fairing for extra security.

I can't recall hitting any ground object as we did a runway check after picking up the pieces. The bracket was badly bent after the incident and I wanted to rebuild the assembly for ideas of cause and when trying to straightening the bracket the bracket broke at that that point.

The runway was a tarmacadam and reasonably smooth. The speed on touch down was 58 kts (from my G3X flight log), although it was a heavy landing.

Regards John
 
Hold the nose wheel off...

Yes - I will be using tinnerman washers or similar in my new nose fairing for extra security.

I can't recall hitting any ground object as we did a runway check after picking up the pieces. The bracket was badly bent after the incident and I wanted to rebuild the assembly for ideas of cause and when trying to straightening the bracket the bracket broke at that that point.

The runway was a tarmacadam and reasonably smooth. The speed on touch down was 58 kts (from my G3X flight log), although it was a heavy landing.

Regards John

My suggestion would be to hold the nose wheel off as long as possible whether on Tarmac or Grass. That goes for landing or takeoff. Just because the mains are on the ground does not mean you have to set the nose wheel down immediately. Hold it off till you cannot hold it off. I have not flown a 14a but in the 7A you can get very slow before the nose has to come down.
 
don't hit the brakes on landing...

My suggestion would be to hold the nose wheel off as long as possible whether on Tarmac or Grass. That goes for landing or takeoff. Just because the mains are on the ground does not mean you have to set the nose wheel down immediately. Hold it off till you cannot hold it off. I have not flown a 14a but in the 7A you can get very slow before the nose has to come down.

Also, make sure you toes are on the bottoms of the pedals on initial landing so you don't accidentally hit the brakes and slam the nose down.... Wait till you absolutely need braking before putting you toes at the top of the pedals and then apply brakes as gingerly as allowable for the runway left, al the while holding what back pressure on the stick it takes to keep the nose wheel off....
 
Hi,

Has anyone had the same experience as me.

RV14 Nose Wheel Fairing Detachment on Landing.

I am in the process of flight testing covering the test schedules of the LAA (light Aircraft Association) in the UK and on landing after only 6 hours of flying the nose wheel fairing detached.

I have attached photos of the damage. I have re-assembled the parts with one layer of glass fibre on the fractured edges to try to establish the cause of the problem.

An idea is that the 8 countersunk screws are not sufficient to hold the Fairing to the Fairing Bracket. Also the large OD diameter of the washer within the Fork Nose axle bolt assembly (Washer 062 25783054) (Page 40A-07) the OD is too small.

Any suggestions of possible causes would be welcome.

Regards John

This design is not exclusive to the RV-14A. It is the same basic design (wheel fairing and brackets) and installation as the RV-10 of which there are almost 1000 flying and 150+ RV-14A's. I don't remember hearing about an issue like this previously.

You don't show any of the hardware in your photos, or mention what was missing or loose. A bit more detail about "the fairing detached" would be helpful.
Are you saying that the fairing detached from the bracket at the 8 screw locations?
If so, did you by chance chase the nutplates with a tap to make the screws easier to install / remove?
 
Don't know how this might affect in the resulting failure, but looking at the pictures and than to the plans, it appears (to me anyhow) the mounting brackets are positioned farther back on the wheel pant than depicted in the plans.
Could the OP measure from the trailing edge of the wheel pant to where the AXLE would be. In the plans this dimension lists as 20 5/32", which would place the forward Allen mtg bolt hole approx 2" or so aft of the front/back pant flange.
If the brackets were mounted slightly aft (pant ending up forward) compared to the plans, I'm unsure if this may cause balance, buffeting, or shimmy issues that might lead to loosened brackets, or fatigue cracking.
Also looking at the pictures, appears the fiberglass was countersunk, possibly too deep and the screws could have worked loose. One way to get past that would be to install Tinnerman (dimpled) washers under the flush screws.
 
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Insufficient Torque Adjustment

I had a similar issue with the front wheel spat at about the same hours of test flying. During the build I applied the torque required in the plans (26 I think).

The aircraft then sat on the front wheel for some time. The plane was towed to the paint shop and back. Unbeknown the torque was diminishing as the front wheel settled down after the initial torqueing.

It was time to go flying. The first few landings were fine. Then all of a sudden the front wheel commenced to shimmy wildly from wheel stop to wheel stop and bingo wheel spat damage (not as much as your photos depict).

I immediately suspected the torque setting had been lost and guess what? It was. Fixed the spat and retorqued the friction setting and 500 hours later nothing has gone wrong.

I'm surprised you did not mention the wild shimming. Therefore, perhaps it was not the same as mine. I warn everyone to re check the torque after your first flight. Vans told me this is common and once you have readjusted the torque setting a second time it should be good for ever. I still check it every annual because I have suffered unintended damage just like you. In five years it have been perfect every inspection. Vans was right you know.
 
Reply to Scott +

Hi Scott,

Thank you for your assistance.

The nose fairing was broken into 4 large pieces and I have repaired the breakage with one layer of glass fibre to assist with finding out what went wrong.

All 4 pieces were found on the runway.

Both brackets were still connected to the wheel hub but one was bent far more than the other. In trying to straighten this one it broke into 2 pieces.

It would appear that all the countersunk holes have been enlarged during the incident. I don't recall chasing the nutplates during building.

It is a mystery to me why this should occur and welcome your involvement.

I have ordered all new parts.

I will check the Torque and the dimensions as other fellow builders have suggested.

Regards John
 
Hi,

Has anyone had the same experience as me.

RV14 Nose Wheel Fairing Detachment on Landing.

I am in the process of flight testing covering the test schedules of the LAA (light Aircraft Association) in the UK and on landing after only 6 hours of flying the nose wheel fairing detached.

I have attached photos of the damage. I have re-assembled the parts with one layer of glass fibre on the fractured edges to try to establish the cause of the problem.

An idea is that the 8 countersunk screws are not sufficient to hold the Fairing to the Fairing Bracket. Also the large OD diameter of the washer within the Fork Nose axle bolt assembly (Washer 062 25783054) (Page 40A-07) the OD is too small.

Any suggestions of possible causes would be welcome.

Regards John

Did you notice a strong shimmy at all? That damage looks as if it could be caused by strong shimmy.

Shimmy has several causes, including improper tire pressure, wheel bearing issues, and improper break-out force.
 
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To Ralph + PCHunt

Hi Ralph,

Just measured and yes the dimensions are wrong.

I've tried to be accurate (can't get a straight line view), however, it would be at least 1 inch to 1 1/2 inch aft from where is should be.

Hi PCHunt,

We felt no shimmy at all -We have flown since the incident and again no shimmy.

Regards John
 
If the fairing detached and left all of the screws behind in the brackets, it was likely caused by either hitting something or a pretty serious nose wheel shimmy event because of an under value nose fork steering friction.

I agree that it looks like the wheel fairing wasn't in the as designed fore/aft position on the brackets but I don't think that in itself would have caused this damage. It also looks like the tabs are the brackets weren't surrounded by flox around their edges, but maybe that is not visible now that it has been broken apart. When done properly, each tab will be captured in a socket molded of flox with the screws primary job being to keep them together, not take shear loads. Especially important if a shimmy event occurs.
 
Fibreglass thickness

John

Looking at your photos, it appears the fibreglass isn’t very thick at the screw holes. I wonder if you’ve missed a step in the instructions.

“reinforce an area about 3” in diameter around each hole with one or two layers of fibreglass”

This step is before doing the flox which creates the recessed area.

If that’s the case I’d suggest checking to see if the main wheel fairings have also too thin an area around the attachment screws.

Looking forward to seeing the -14 in UK skies

Regards

Peter
 
Without Thinnerman washer ... it will pull the screw thru the fiberglass ...
Fiberglass, so thin and with such a small contact area, countersink makes it even worse.

That the rear cone broke off, shows that there was some shimmy. This happens to an RV-10 in Switzerland too.
The reason was, that the fairing was NOT exactly according to plans mounted/attached and a light shimmy brought it to "unlatch at the bolt",
followed by disrupture of the fairing bracket and wheel pant. The point was, that the engagement with the smaller/bigger washer was not correct.
The bracket is not clamped by the screw and the big washer, is just engaged around 270° by the big washer and kept from slide off the bolt.

See sketch how it should be:
ACtC-3e1n-fFC4Q2SifXIJrV0zcSKkV2Sdx2gJjzMcQ5qqThuuHUXtN0PviYCo2wjnFZKeULAfKb8p1lQ9mKJT_u2kFtRL3Ld-uZ4kImj7-coMKPbsjCuc1X91iLizd9ytDeq-r2KbgWcA31p0raovG8Ry6M=w694-h554-no
 
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Nose damage

I watched a nose wheel fairing come off on an RrV-10 The nose touched down first and bounced. When that happened the shimmy sent the wheel to its stop where it stayed until the nose touched down for the second time. The whip of the wheel from the stop caused the fairing to separate . The solution of course is to keep the nose off until speed is reduced and only touch the nose down once.

-Andy
 
Hi,

Thank you for all the comments and suggestions. All will be taken on board and incorporated in my new nose fairing.

What a brilliant platform this is.

Regards John
 
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