Results of Cable Replacements on High Time PA31-350s

[jmmiller]

We recently replaced all of the Flight Control Cables on one of our older Chieftains (Year Model 1976 with 35,000+ TTAF). We found several areas that had signs of wear and corrosion that are not normally discovered during normal inspection events.

There were some places to note: One spot was on each of the Rudder Control Cables where they attach to the Left and Right Pilot's Rudder Pedals and run down along the Forward Bulkhead. It seems that the cables are rubbing on the factory installed plastic-covered insulation on the bulkhead. The arc of the Rudder Pedal Attach Point looks like it is causing the cable to rub excessively on the hard plastic when the cables are moved to their extreme positions during ground handling, steering and when the controls are exercised prior to flight. It's not a normal position to achieve during flight. Seems like the wear is about 3" to 6" below the Rudder Attach points.

Another area to note is the cable pass through area in the fuselage. It's a place where condensation can form and can cause corrosion. Some of the cables had significant corrosion embedded in the strands and it wasn't easily noticeable until the cables were removed from the aircraft.

We also found an area of the Aileron Cable that is hidden between two ribs just inboard of the outer Bellcrank that had a wear area that can only be seen by removing the cable from the Bellcrank and drawing it through the two ribs.

We will be producing an exhaustive report of our findings soon. We will post it here when it is available.

In the meantime, have a Merry Christmas and a Happy New Year!

Joe M Miller
Warbelow's Air Ventures, Inc
Fairbanks

[Tim Glubaskas]

We finally have a small report to share on these areas - -

Though we inspect these cables regularly, we have identified several areas of wear - some of which we weren't expecting or that are hard/impossible to see without removal of the associated cable

The good news is that none of the items had reached a critical stage and that most cables were performing well even with high time


A small report will be posted in this thread so that others may focus in on these areas and see if they, too, find the issues we have identified

As we replace more full sets we will update our results as needed - we are planning to replace all cables in Aircraft greater then 30,000 hours to start and based on further findings we will go from there


Any input/findings from other operators is appreciated

[jmmiller]

Here's the report we have been talking about. Hopefully it will help shed some light on a few problem areas that we have identified.

Piper Navajo Chieftain Cable Report.pdf (486.46 KB)