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Last week, whilst taxiing, I noticed "squeaking door" sounds coming from the
main gear area -- especially during turns.  This was also noted when
returning the plane to the hangar.  A fellow LNC2 builder thought this might
indicate delamination of the over-center link/spar attach point (See Service
Bulletin SB50-0999, GM13 secondary main gear attach point).  Visual
examination revealed that this was not the case (SB not yet implemented).  
However, aural examination (stethoscope) focused on the bolt as the source of
the screeching sounds while a helper was pushing on the wings to produce a
side load on the gear.  

At least a 3/4 turn was required to re-torque these bolts to the proper
tightness -- All the unseemly noises stopped!

It has been my experience that, over time, fiberglass can move, flow,
compress, etc.   I would recommend that all fiberglass/phenolic supported
critical bolts be inspected/retorqued at 100 hour or annual inspections.  
These include main gear forward attach points, nose gear actuator attach
point bracket, engine mount bolts, outboard rear spar attach bolts and any
others so mounted.  Wing main spar bolts pass thru bushings imbedded in
carbon and aluminum plates -- These should not need re-torqueing, but should
be inspected.

Note:  Landing gear final mounting, 1994. First flight in 1996 with 220 hours
and 250 landings since then (probably 230 takeoffs - some landings were
multiple events).

Scott Krueger
N92EX


 
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Please send your photos and drawings to marvkaye@olsusa.com.
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