Looking for Flap Cables

[Paul462]

If this was previously reported, please forgive the repetition. I talked with a missionary flyer last Sunday who reported a 337 crashing during this last year in Copan Guatemala (if I recall the location correctly). This was described as a fairly short, up-sloping runway - sounded challenging. It was probably a short field landing. Upon flap extension, only one flap extended but the other didn't. The aircraft commenced roll and impacted a deep crevasse just short of the runway. There were six souls on board; all survived, apparently un-injured or with only minor injuries.

The missionary, an extremely experienced bush pilot, blamed himself for not reacting faster in retracting the flap(s) to restore control.

The account I heard may have been in error regarding the failure sequence - perhaps the flaps were already extended when one snapped up.

A semi-happy ending for all except the unfortunate airplane. And a reminder for us all to be primed to quickly retract the flaps and add full power in case of un-commanded roll. This makes it important to have props forward and mixtures full rich when turning final, before extending full flaps.

Should we have the props forward and mixtures full rich whenever we extend any flaps at all? Or maybe do this turning base, instead of on final? This assuming we're close to sea-level flying a normally aspirated Skymaster.

[Ernie Martin]

Because some of the info on this thread did not conform with earlier knowledge, I spoke to Don Nieser about checking the cables.

It's true that a thorough visual and cotton swab/rag inspection may not detect a cable that may have a few broken strands, but we believe that it will allow you to make a determination on whether the cable is sound or should be replaced.

The fact that there are 100 or more strands and the typical design margin lead us to believe that a cable inspected thoroughly (visual and cotton swab/rag) and found to have no broken strands is good for continued service until the next annual.

I would add that it's not a bad idea to include this in your landing checklist: Flaps up immediately if aircraft rolls.

Ernie

For what it's worth, the reason I made my comment is because I've changed flap cables myself, I'm an AME here in Canada,. On one Skymaster, visually inspecting the cables before they were removed showed nothing. Once removed one cable had around 40-50% of the cable strands broken. There was no way of seeing this. With half the cable strands broken I question how much strength is left in the rest of the cable.

[Ernie Martin]

Tony, that changes everything. Question: it was a thorough visual, with flashlight and cotton swab/rag? And showed nothing, no fraying of the cotton? If that is the case, then I retract my prior message, and I'm sure Don would too.

Ernie

[rick bell]

just a thought - i would think that cycles induce wear, base on that theroy low time and
less cycles would produce less wear. with one exception, some a/c had sheet metal screws that were too long and rubbing on the cable. year back i checked that and mine were. just replace the screw with a shorter one. it did not indicate any wear or broken strands; but that
was with 800.0 now it's 2000.0.

one could always drop the flaps well below the 160 maybe at the low end to reduce cable
tension and you really don't need them on takeoff, just a thought.

Originally Posted by Ernie Martin

Tony, that changes everything. Question: it was a thorough visual, with flashlight and cotton swab/rag? And showed nothing, no fraying of the cotton? If that is the case, then I retract my prior message, and I'm sure Don would too.

In this particular case we were changing the cables on spec. It was a few years ago so I can't remember the exact details. If I recall correctly, I gave them a visual inspection and ran my finger over what I could access and didn't find any problem. Once the cables were removed we were quite surprised to see them as bad as they were.

When I did my skymaster it was pretty much the same thing. Although the cables weren't frayed as bad.

[SkyMac]

Hi Everyone

Just keeping you all informed on what I find as we continue with the project, there has been a lot of information recently regarding flap cables and replacement.

Having just removed cables and bell cranks from L/H wing in preparation for replacing the cables. Even though the flap cables functioned and showed little signs of wear prior to aircraft dissasembly, a small number of internal wires were broken - TTAF 1958hrs. No record of previous replacement.

Regards
Dave

[hharney]

I cannot find any part #1460100-307 flap cable. Don has none and all the Cessna sites are out of stock. Does anyone know of any available???