Wings make odd noise…

[SlowRoll]

I recently read in an article of an older german magazine, that during pre-flight inspection, as part of the wings check, when rocking them up and down holding them at the wing-tips, no “cracking” noise should be heard. If “cracking” is heard, flying would be a very bad idea instead, wings assembly should be thoroughly checked.

Now to my question: as a co-owner of a lovely Pilatus P3 I always hear this odd “cracking” when rocking the wings up and down, especially if during the previous flight aerobatics were performed.
I never thought this could be a problem, till I stumbled across that article, as I assumed that under the stress of aerobatics the wing would slightly flex and the skin with it…..it would then make a “cracking” noise where the aluminium sheets are riveted together, when some sort of tension was released by rocking the wing. In fact, this odd noise is to be heard only once. Repeated rocking of the wings will not result in repeated hearing of the odd “cracking”.

What do you think I should do guys ?? Have you ever experienced something similar ?

Cheers

SlowRoll

[LowNSlow]

As it is now lodged in your mind and may impair your enjoyment of the P3 (lucky chap) maybe it would be worthwhile demonstrating the 'cracking sound' to an engineer experienced on the type. Hopefully he will be able to put your mind at rest without emptying your bank account :D

As an afterthought, how old was this article? Were they referring to aircraft with wooden main spars or was it a general statement covering all aircraft construction methods?

I waggle the wings before I fly just to make sure they're screwed on. I get some creaks but no clunks. Clunks mean something lose and pushing the bird back into the hanger!!!!

[SlowRoll]

Thanks for your reply LowNSlow!

The magazine is 3 to 4 years old and the article was about things to watch out for when hiring an aircraft. It was not particularly related to aircraft with wooden main spar.

The next time I have the chance, I will get an engineer with experience on type to look at the "problem".

Cheers

SlowRoll

[bingoboy]

I used to waggle the wings of an old biplane I used to fly because an old engineer once told me to make sure the wave/flexing continued to the fuselage and even to the other tip. Seems if the spar (wood) were cracked the ripple would stop.

Well I was never too sure of the logic but I always did it so I feel confident that I never flew with a cracked spar !!!

Wonder what other funny/odd/strange habits we develop prior to flight ?

[ShyTorque]

Before losing too much sleep, hold out your arms and carry out a similar movement without actually holding the wing.

If you can still hear the cracking noise, the aircraft is OK and a visit to the chiropractor might cure it altogether. :D

[LowNSlow]

bingoboy my dad used to pee on the tailwheel of his Halifax. Don't recommend it nowadays though, the PC Police would have you locked up before you could pull up the zip at most airfields :D:

[Reichman]

With reference to Bingoboys reply:

I remember many moons ago being told be a quite well known glider repairer that if you held one wing tip and gently wiggled it up and down the other tip should do exactly the same at the same frequency. If it didnt then there was a major crack in the spar. This worked for glass fibre and wooden spars - don't know about metal ones.