NTSB Factual Report

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.

NTSB Probable Cause

An in-flight encounter with unforecast turbulence, which resulted in structural damage to the stabilator.