Piper Control Cable AD (does not apear to affect Comanches)

[Charles Schefer]

The following appeared on AV Web this morning. From the written description it does not appear to affect either single or twin Comanches but I wonder. Other Piper types are referenced (Comanches are not) but the coming AD appears targeted at "older Piper aircraft" so I wonder if it could end up including Comanches. Just posting as an FYI.

- Charles

From AV Web on 2/4/2013:

Control Cable AD Coming For Pipers

Piper Aircraft has confirmed the FAA will issue an AD on Monday requiring specific inspection, at annual, of the control cable assemblies of tens of thousands of aircraft that are 15 years or older. The AD will affect Cherokee, Saratoga, Lance and Seminole models. It will at first apply to the older aircraft but as each of the remaining aircraft hits its 15th birthday the inspections will become mandatory. Eventually 34,000 aircraft will be affected. Piper spokeswoman Jackie Carlon said the company has already issued a service bulletin and mandatory service bulletin regarding the control cable inspections and "cooperated fully" with the FAA in developing the AD.

The AD results from three incidents in which control cable problems were implicated. Carlon said the problems should have been caught during the normal annual inspections. "In the three reports cited, evidence of approaching failure should have been clearly observable during the Piper-mandated 100 hour recurring inspection schedule," Carlon said in a statement first issued to the Wall Street Journal and then provided to AVweb. "Considering that there are tens of thousands of the indicated Piper models in operation in the past 50 years, the historical data demonstrates that trained mechanics can identify these conditions before failure occurs. Reinforcing these inspection procedures will be helpful to maintain Piper's safety record." Piper says it will help owners determine if their aircraft are affected immediately.

[md11flyer]

I am not sure, but I believe the cause of the failures were due to seized pulleys on the those aircraft.
The pulleys will then wear the cable to the point of failure. All of the models in the ad have the same type pulleys with bushings, whereas our comanche pulleys have bearings. I suppose they could also seize but less likely.
Its pretty much a moot point anyway as these items are checked during the annual anyway so its not a big deal.
For the guys that don't pull the floor boards each annual its still verily easy to check the cables and the pulleys for proper
condition through the access covers on our machines. Maybe on the other types its not so easy to check.
I am sure nobody will squawk about having this check done, knowing that there are cables failures in other airplanes and the fact its part of the annual check anyway.
Or am I out in left field on this?

Gary

[Charles Schefer]

[Charles Schefer]

Here's an update on this AD (which does not affect Comanches - Single or Twin) but does affect MANY Pipers. Yesterday I met with my FAA Principal Maintenance Inspector (PMI) who oversees my 135 Op. Small world coincidence... it turns out he is the author (or co-author) of that AD.

Apparently the AD is the result of two incidents: In my area a PA-32 Lance that just completed annual was on a flight review with the owner and an instructor. During the landing flare the elevator control cable snapped. There were no injuries. In another incident a Piper Cherokee had the same thing happen at altitude. This second incident (which actually happened first) was fatal.

My PMI who was investigating the Lance incident compared notes with the inspector reviewing the fatal crash and the cause was the same... on the control cable there are is a turnbuckle with a swage at either end allowing adjustment of cable tension. In both cases the cable pulled loose or broke where it is crimped on to the swage. Apparently Piper recommended (via SL or SB?) inspection using a magnifying glass but this is not regulatory. At most annuals the standard inspection (I have been told) is to run a rag down the control cables looking for frays. This would not catch the swage problem.

I asked why Comanches are not affected. Apparently it has to do with the way the swage was attached to the cables on the aircraft types that are affected. In the aircraft that are affected (all Vero Beach production I think) the swage was crimped on and heat was applied. It sounded from my PMI said that the heat was part of the issue and the crimp became brittle over time. Apparently the way Comanche cables are set up is different and they don't have this same type of swage-cable crimp and / or heat was not used in Comanche cables.

- Charles