Piper’s long-running preference for stabilators began with the PA-24 Comanche. A&P/IA KRISTIN WINTER discusses the stabilator system and its most common problems, as well as what you can do to keep your tailfeathers airworthy.
The Piper PA-24 Comanche was the first Piper production aircraft to use an all-moving stabilator instead of the more common horizontal stabilizer and elevator combination. Piper obviously liked the result, as they used stabilators in the Aztec and in all the Cherokees and their derivatives.
Piper stabilators have proven to be fairly robust, with only a few issues that can easily be addressed with heads-up maintenance. In this piece, we will look at the known issues with Comanche and Twin Comanche stabilators.
Torque tube horn cracking
The stabilator system had been reasonably AD-free until 2012, when the FAA issued AD 2012-17-06, which addresses cracking in the torque tube horn that attaches the counterbalance arm to the torque tube, to which in turn the stabilator halves are attached.
The cracks propagate from the inside, as all three of the cracked horns in the photo show (See photo below).
The cracks progress from there to the outside, and eventually, a secondary crack will propagate on the aft side, as cracks in the front have now progressed to the point there is relative movement inside the horn. Once this happens, complete failure of the horn is likely but a few flight hours away.
Please login to continue enjoying members-only content
This section of the article is only available for our members. Please click here to join to view this part of the article. If you are already a member, please log in.