Piper PA-28RT-201 N2091W incident near Chesapeake, Virginia

Probable cause

Maintenance personnel’s inadequate inspection and compliance with a Federal Aviation Administration airworthiness directive, which resulted in an undetected corroded and cracked stabilator turnbuckle and the subsequent failure of the turnbuckle and loss of elevator control during takeoff.

NTSB analysis

The pilot and safety pilot reported that, during takeoff, they heard a loud "pop" as the pilot increased the angle-of-attack to become airborne and that the airplane then pitched down. The airplane became airborne momentarily and then the safety pilot aborted the takeoff. The airplane touched down on the runway in a three-point attitude.

Examination of the airplane revealed that the aft lower stabilator flight control cable's turnbuckle assembly had broken at the aft cable terminal fitting and that the control cable terminal had fractured due to stress-corrosion cracking. Federal Aviation Administration Airworthiness Directive (AD) 2013-02-13 and Piper Service Bulletin (SB) 1245A were issued to address the failure of the control cables. According to the airframe and powerplant mechanic's logbook entry for the most recent annual inspection, which occurred 6 flight hours before the cable failure, he had complied with AD 2013-02-13 by inspecting the cables in accordance with Piper SB 1245A. The SB instructed the mechanic to disassemble the turnbuckle assembly and clean it using a solvent, such as acetone, or a general purpose scouring pad and then to use a 10x magnifier, a mirror, and a suitable light source to inspect each turnbuckle, cable terminal, and adjacent portion of the cable. Any evidence of cracks, cable fraying, or corrosion was cause for replacement.

Further examination of the terminal fitting indicated that it was covered in many areas with deposits that were likely a mix of corrosion products, grease, and dirt, and, therefore, that it had not been cleaned sufficiently to allow for an effective inspection. No scratches were observed on the surface, indicating that a scouring pad had not been used. The deposits observed on the turnbuckle were unable to be readily removed without a scouring pad, indicating that they were likely there longer than the month since the inspection occurred.

Text from the NTSB. Open the NTSB docket for ERA13IA396 for the full record.