ERA13IA396

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.

On August 31, 2013, about 1345 eastern daylight time, a Piper PA-28RT-201, N2091W, experienced a pitch control failure during takeoff at Hampton Roads Executive Airport (PVG), Chesapeake, Virginia. The airplane was undamaged and the two pilots were uninjured. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight, which was operated under the provisions of Title14 Code of Federal Regulations Part 91. According to the pilots, the purpose of the flight was to familiarize themselves with the airplane. During takeoff, as they increased the angle of attack to become airborne, they heard a loud "pop" and lost pitch control. The airplane became airborne momentarily and then touched down on the runway in a three point attitude. Neither of the pilots was injured, and the airplane was undamaged. Examination of the airplane revealed that the aft lower stabilator flight control cable's turnbuckle assembly had broken at the aft cable terminal fitting. Examination of the turnbuckle and aft cable terminal fitting by the NTSB Materials Laboratory revealed that the cable terminal had fractured in the shank region about 0.25 inches from the wrench flats. Areas of the turnbuckle were covered with a white crystalline material, and the shank adjacent to the fracture exhibited reddish orange deposits. Examination of the fractured region with a 5X to 50X binocular zoom stereomicroscope also revealed that the fracture surface was rough with crack branching, which was consistent with stress corrosion cracking. Cleaning of the terminal in the area of the wrench flats and adjacent shank areas using acetone and a scouring pad comparable to a Scotch-Brite general purpose green scouring pad also revealed that some of the reddish orange deposits remained in some of the crevices on and adjacent to the wrench flats. Isolated areas of small pits were also observed on the turnbuckle shanks with a higher density of pits being observed on the outer diameter at the wrench flats. Additionally, a longitudinal crack was discovered at the end of the terminal adjacent to the cable. The area around the crack was also cleaned using acetone and a paper towel, and reddish orange deposits remained adhered to the surface after cleaning. Review of Federal Aviation Administration (FAA) records revealed that the turnbuckle assembly was the subject of FAA Airworthiness Directive (AD) 2013-02-13, which was prompted by reports of cable assembly failures that led to failure of the horizontal stabilator control system and resulted in loss of pitch control. This AD required inspection of the stabilator control system and replacement of parts as necessary. According to FAA and airplane maintenance records, the airplane was manufactured in 1979. The airplane had recently been purchased and was going to be placed in a local operator's fleet for rental and use in their pilot training program. As part of the purchase it had undergone an annual inspection on July 21,2013. At the time of the inspection, the airplane had accrued 6,100.3 total hours of operation. At the time of the incident the airplane had 6,106 total flight hours. According to the airframe and powerplant mechanic's logbook entry for the annual inspection, Airworthiness Directive (AD) 2013-02-13 (effective March 11, 2013) had been complied with during the annual inspection by inspecting the cables in accordance with Piper Service Bulletin (SB) 1245A. The inspection as described in SB 1245A required that the mechanic disassemble the turnbuckle assembly and clean it using a solvent such as acetone. Use of a Scotch-Brite general purpose green scouring pad was also permitted for cleaning. A 10x magnifier, a mirror, and a suitable light source were then required to be used to inspect the turnbuckle, terminal, and adjacent segment of cable. Any evidence of cracks, cable fraying, or corrosion that remained after the cleaning was cause for replacement.