Loss of Control in Flight · NTSB WPR20LA135

Piper PA-23-250 — Hemet, CA

1 fatal High-time pilot
DateApril 30, 2020
LocationHemet, CA
AircraftPiper PA-23-250
Purpose of flightOther Work Use
ConditionsDay · Visual Meteorological Cond
Phase / occurrenceEnroute Flight control sys malf/fail
Pilot age27
Pilot total time1,138 hrs · Experienced
Time in type379 hrs
Fatalities1

Probable cause

Maintenance personnel’s failure to properly inspect and replace damaged aileron control cables, which resulted in fatigue separation of the aileron control cable and loss of control of the aircraft.

NTSB findings

  • Aircraft-Aircraft systems-Flight control system-Aileron control system-Fatigue/wear/corrosion
  • Personnel issues-Task performance-Maintenance-Scheduled/routine maintenance-Maintenance personnel

What happened

The accident pilot and a second company pilot were flying in the same general area to photograph parcels of land. As the pilots were beginning their photography passes, the company pilot heard the accident pilot make distress calls on the radio. The accident pilot did not respond when asked to clarify the radio calls.

ADS-B data revealed the airplane approached the area to be photographed from the west, made a turn north to enter the area, then made a turn back to the southwest. The airplane then started a right descending turn about the time it intercepted its inbound course to the area. The last data captured the airplane, about 1,000 ft above the ground, about 177 knots groundspeed, in a 2,000 ft-per-minute descent, and about 950 ft northwest of the accident site. The camera system mounted in the airplane recorded the airplane, at that time, in a 31° nose-down attitude, and a 79° right roll.

The airplane struck steep mountainous terrain at a high speed, and the fuselage sustained substantial damage throughout. The wings, the vertical stabilizer, and the right side of the stabilator separated from the airplane.

Examination of the aileron control by the NTSB materials laboratory revealed that a cable had broken under fatigue in a location near the aileron control bellcrank, likely resulting in a loss of control of the airplane. The airplane was maintained in accordance with the operator’s annual maintenance schedule; however, postaccident examination of the aileron control cable revealed that in addition to the fatigue break, multiple individual broken wires were discovered protruding from the strands, which would have required replacement of the cable upon discovery during required checks of the cable.

The toxicology report for the pilot identified positive results for a cannabis metabolite; however, amounts discovered were unlikely to have been impairing. Given the circumstances of the accident, it is unlikely that the pilot’s use of cannabis contributed to the accident and that the pilot lost control of the airplane due to the fatigue failure of the aileron cable.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.

View the official NTSB docket →