[Thumper]

So......

My next technical query i'd appreciate feedback on is...

When an aeroplane suffers a heavy landing to the extent an undercarriage leg ends up a few degrees from being parallel with its other leg, would you expect the forces that caused the bend to be confined to the u/c or, to have spread into other areas of the airframe, causing potential similar but unseen damage.

This really is an open question - and i apologise for that - obviously there are lots of factors at play but....

where the port u/c and tailwheel both needed repair, my cautious non-engineering background would lean towards stripping the fuselage fabric (although it shows no creasing, damage) and measuring/checking the metal tubing for other hidden gremlins...

...or did the u/c leg do its job by bending so damage was local..shot peening further disclosing the extent of the 'injury' and therefore i'm being over cautious.

as ever, feedback from you is most appreciated.

tty

[Flyin'Dutch']

It pays to be careful in the scenario you picture.

Much will depend on the type of aeroplane and the accident mode.

What was the motivation for not looking under the fabric at the time?

[Thumper]

That's a good question to ask. Didn't think of that one. i guess it was the pain of uncovering and recovering. However, the more i think about it you have to be going some to twist an u/c leg and thump a tailwheel upwards so you loosen its vertical fixing.

[Flyin'Dutch']

It really all depends on the aeroplane type and the accident sequence.

Some undercarriage legs are very vulnerable to side-loads and will sheer off easily but that is by design to protect the spar to which they are attached.

Making and repairing a hole in fabric to have a good look is very easy and very straightforward and should come easily within the competency of anyone able to fix a bodged undercarriage.

[Thumper]

It really all depends on the aeroplane type and the accident sequence.

Some undercarriage legs are very vulnerable to side-loads and will sheer off easily but that is by design to protect the spar to which they are attached.

Making and repairing a hole in fabric to have a good look is very easy and very straightforward and should come easily within the competency of anyone able to fix a bodged undercarriage.

there were definitely no patches inspecting other parts of the u/c section.

[Flyin'Dutch']

there were definitely no patches inspecting other parts of the u/c section.

Maybe a whole section was made bare and recovered.

They should be able to tell you what was done and by whom and then you can make up your mind as to whether you are happy with the current state - you might want to ask someone in the know if they know the person who did it and what they would expect to have been undertaken.

Maybe the sort of follow on questions which are best placed in a PM to the right person.

[PeteSpencer]

You are right to be cautious about hidden damage:

While not related to the undercarriage or even metal structures I remember a fatal accident report about 15 years ago concerning IIRC a Jodel or Robin which deviated from the runway on landing and the wing struck a large hay bale.

The pilot was seen to get out and inspect the wing and apparently found no visible damage.

Later when he took off the wing fell off and he died.

Peter

[Dave W]

It was G-DELS, a Robin DR400 at Kemble.

The structural failure of the wing occurred on the way back to Cornwall; here's the AAIB report.

[Charles Hunt]

Any connection to your forum name?

[Charles Hunt]

Dave. Horrible reading.

[Dave W]

Very much so.

(Horrible reading; not my forum name)

[Charles Hunt]

Ah, sorry, that was for the OP. Heavy landings....Thumper.....alright, suit yourselves.

[PeteSpencer]

That's the one , Dave, but the report I saw had diagrams etc (indeed 'fig 3' is referred to in your AAIB link.

Peter

[Sooty25]

Going back to the original post, @Thumper you could always have inspection plates fitted into the fabric which then allow an amount of access for visual inspection.

We have a pair in fabric wings, circular about 4-5" and can be popped out for access. Allows access with an endoscope type camera for poking in further.

here is a link to the plate
http://www.aircraftspruce.com/catalog/cspages/inspectplate.php

And these are the rings you bond to the fabric.
http://www.aircraftspruce.com/catalog/cspages/inspectring.php

For what they cost and maybe getting your inspector to fit them at the same time as inspecting for damage, cheap piece of mind.

[Rob L]

Here is a hint on installing a new inspection ring on existing fabric. Particularly useful if two-pack paint has been applied as a top coat.