ANC11LA027

The pilot reported that while descending toward his destination, the airplane encountered severe turbulence of short duration. After the turbulence passed, he made an uneventful landing at his destination airport. A postaccident examination of the airplane discovered substantial damage to the stabilator. The wind at the destination airport was reported as 310 degrees at 9 knots, the area forecast valid at the time of the turbulence encounter forecast no significant turbulence, and there were no pilot reports of turbulence. The pilot indicated that prior to the severe turbulence; there had been no significant turbulence during the flight. An examination of the stabilator showed that the right half was bent downward 5 to 10 degrees outboard of the fuselage attachments. No evidence of fatigue or corrosion was found.

On April 14, 2011, about 1755 Alaska daylight time, a Piper PA-32 airplane, N81052, sustained substantial damage during an encounter with turbulence in cruise flight, about 13 miles west of Cold Bay, Alaska. The airplane was operated by Peninsula Airways, Inc., Anchorage Alaska, as a visual flight rules (VFR) cargo flight under 14 Code of Federal Regulations, Part 135. The solo airline transport pilot was not injured. Visual meteorological conditions prevailed, and company flight following procedures were in effect. The flight departed False Pass, Alaska, about 1745. In a written statement to the National Transportation Safety Board (NTSB) dated April 29, the pilot wrote that while descending toward his destination, the airplane encountered severe up and down drafts. During the encounter, the pilot hit his head on the sun visor, even though his seatbelt and shoulder harness were snug and secure. Afterward, he continued to his destination, and landed without incident. The wind at the destination airport at the time of the accident was reported as 300 degrees at 9 knots, the area forecast valid for the time of the accident, forecast no significant turbulence during the reporting period, and there were no pilot reports of turbulence in the area. The pilot said there were no preaccident mechanical problems with the airplane. A postaccident examination discovered substantial damage to the stabilator. An examination of the stabilator by the NTSB investigator-in-charge showed that the right half of the stabilator was bent downward 5-10 degrees outboard of the fuselage attachments. The bottom skins adjacent to the bend were wrinkled. The skins were removed, and revealed downward bending of the stabilator main spar. No signs of fatigue or corrosion were found.