Skymaster down!

[Paul462]

If memory serves, there was quite a comprehensive broken flap cable thread on this message board 6 or 7 years ago after the Australian failure. I believe that one occured on short final, a few hundred feet up, and the pilot reported he applied full power and retracted the asymetrically extended flap. It goes without saying he was probably applying full ailerons and coordinated rudder against the roll... :-)

Unfortunately, it is not possible to visually or "rag" inspect the flap cables in place, or even removed from the aircraft, because the heart strand or an internal strand may be failing, and that would not be visible externally, even with the cable removed. Also, the most common failure point is flush against a quadrant pulley, not easily inspectable.

There are FBOs who are willing to take your money for a "visual" inspection - Turbo Air in Boise Idaho did from me back in 2003 when I bought my first 1968 T337C, as part of a $7,000 annual! They called it a "visual" and "rag" inspection - you drag a rag along the cable and see if it snags anywhere, and "visually" inspect where you can't reach with the rag. This inspection was at least partly ineffectual, because it only inspected external strands, not (possibly) failing internal strands nor the heart strand.

I took a different approach with my second T337C, acquired 2 years ago with just under 3,000 hrs. TTAF: we removed the 4 flap cables which hold down the flaps and replaced them. It wasn't that awful bad a job (10 - 12 hours?), and the IA made up new cables on the spot with new terminals and cable, using a huge swedger he dragged over. I understand there's an operation in New Zealand which does same every 500-1,000 hours or so, as preventive maintenance.

[edasmus]

Thanks for this info Paul! Much appreciated!

Ed

[birddog]

Does anyone know the history on when the factory went to stainless steel cables and have any of the accidents involved stainless steel cables? I understand later production aircraft were all manufactured using the stainless steal. I have heard one report that none of the flap failures involved the stainless steal equiped aircraft. This is a significant observation if true. The source did not give permission to use his name but it's a very reliable source in the 336/337 aircraft operations. OK I like cooberation. I think thats the right word.
________
Weed vaporizer

[WebMaster]

If you buy new flap control cables, they are stainless steel.

[Kim Geyer]

We replace our cables at 3000 hrs or when we add the airplane to our fleet. I've pulled out 1800 hr cables and found broken strands and I've pulled 4000 hr cables an they were good. We replace them with stainless steel and before I install the I let them soak overnight in a Mil spec cable lube that I used on Sabreliners. It takes @ 6 or 7 hrs to change them and rigg the flaps. I also found that it is easer to remove the cable pulleys rather then removing the guard pins. They can be almost impossable to get them back in and bent over.
Hope this help
Kim

[Kim Geyer]

The crash of the 337 doing fire work could have been caused by the pilot making 360's at low level and flying into his own wake turbulance. this may have been what happened to an O2 a few years ago doing whale surveys off the Fla coast.
Kim