# NTSB ANC98IA004: Cessna 208B, N9304F, Kasigluk, AK, October 20, 1997 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: October 20, 1997, 10:00 local (18:00 UTC) - Place: Kasigluk, AK - Coordinates: 60.869823, -162.539596 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=60.8698&lon=-162.5396&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report November 10, 1998 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 3098 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC98IA004 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/3098/pdf - Page: https://openairdocs.org/ntsb/ANC98IA004 ## Probable cause inadequate inspection of the aileron by company maintenance personnel, and the pilot's inadequate preflight inspection of the aileron, which led to the jamming of the left aileron due to loose balance weight retaining screws. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, approach - vfr pattern - downwind - flight control,aileron - jammed (cause) - maintenance,100-hour inspection - inadequate, company maintenance personnel (cause) - aircraft preflight - inadequate, pilot in command (cause) ## Analysis The pilot was entering a left downwind for landing at a remote airport. The wind conditions were 25 knots with gusts to 35 knots. During the turn, the pilot utilized full aileron deflection, and noticed the aileron momentarily jammed. He was able to force the control wheel to the right, unjamming the aileron. After landing, the pilot began to taxi to the ramp. Due to a strong crosswind, the pilot deflected the ailerons fully to the left. The aileron once again jammed, and the pilot was unable to force the control wheel to the right. The airplane's ailerons utilize balance weights that are attached to the interior surface of the leading edge of the aileron. Five screws are inserted through the leading edge skin of the aileron, through the balance weight, and into self-locking nuts attached to a nut strip assembly. Company maintenance personnel reported 1 screw was missing. Three of the remaining 4 screws were loose, and backed out sufficient distance to contact the trailing edge of the wing, forward of the aileron. The left aileron was jammed in a full, leading edge down, position. The Cessna 208B pilot information manual details a preflight inspection that includes an examination of the ailerons as part of a walk-around inspection of the airplane. In addition, the balance weights should be inspected during every 100-hour inspection. A review of the manufacturer's service condition report data base, and the Federal Aviation Administration malfunction and defect report system did not reveal any other reported incidents of aileron jamming. ## Factual narrative On October 20, 1997, about 1000 Alaska daylight time, a Cessna 208B airplane, N9304F, had a left aileron jam during the landing approach to the Kasigluk Airport, Kasigluk, Alaska. The airplane was being operated as a visual flight rules (VFR) nonscheduled cargo flight under Title 14 CFR Part 135 when the incident occurred. The airplane, operated by Peninsula Airways Inc., Anchorage, Alaska, was not damaged. The certificated airline transport pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed. VFR company flight following procedures were in effect. The flight originated at the Bethel Airport, Bethel, Alaska, at 0930. The pilot reported he was maneuvering to land on runway 35 at the Kasigluk Airport, and began a left turn to enter the downwind portion of the landing approach. During the turn, the pilot utilized full aileron deflection, and noticed the aileron momentarily jammed. He was able to force the control wheel to the right, unjamming the aileron. The pilot continued the landing approach, and landed without encountering further control problems. The pilot indicated that following the landing, he began to taxi to the ramp. Due to a strong crosswind, the pilot deflected the ailerons fully to the left. The aileron once again jammed, and the pilot was unable to force the control wheel to the right. The operator reported the incident flight was the first flight of the day for the airplane. The airplane ailerons utilize balance weights that are attached to the interior surface of the leading edge of the aileron at the inboard, and outboard ends of the aileron. Five screws are inserted through the leading edge skin of the aileron, through the balance weight, and into self-locking nuts attached to a nut strip assembly. Company maintenance personnel conducted an inspection of the aileron, and reported 1 screw was missing. Three of the remaining 4 screws were loose, and backed out sufficient distance to contact the trailing edge of the wing, forward of the aileron. The left aileron was jammed in a full, leading edge down, position. The operator's maintenance personnel replaced the screws, and did not report any obvious failure or damage to the attaching screws. The operator found slightly loose balance weight screws in other Cessna 208B airplanes. In each case, the self-locking nutplates still had proper grip. The operator indicated their maintenance department personnel have since applied loctite to each screw. The Cessna 208B information manual provides a description of a preflight inspection that includes an examination of the ailerons as part of a walk-around inspection of the airplane. In addition, the balance weights should be inspected during every 100 hour inspection. A review of the manufacturer's service condition report data base, and the Federal Aviation Administration malfunction and defect report system did not reveal any other reported incidents of aileron jamming. ## Aircraft - Registration: [N9304F](https://openairdocs.org/aircraft/N9304F), registered now, S/N 20800008, built 1985 (OpenAirDocs) - Reported make and model: Cessna 208B - Registry model: [Cessna 208](https://openairdocs.org/model/cessna-208) (registry code 2073702) (OpenAirDocs) - Registry engine: [Pratt & Whitney PT6A series](https://openairdocs.org/engine/pratt-whitney-pt6a-series) (registry code 52032, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 20800008 - Airframe hours: 8638 - Engines: P&W PT6A-114 600 horsepower turbo prop - Damage: No damage - Flight: Part 135 - Operator: Peninsula Airways Inc. - Registered owner: Avion Capital Corp. - Airworthiness certificate: Standard, Normal - Last inspection: Continuous airworthiness, September 25, 1997, 34 hours before - Departed: BET, BETHEL, AK - Destination: Z09 - Flight plan: Company VFR - Airport: Z09, Kasigluk, runway 35, 1,950 × 50 ft, gravel ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 35; commercial, airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; flight hours: 5,800 total, 150 in this make and model, 5,500 as pilot in command, 180 in the last 90 days, 60 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 315° at 25 knots, gusting 35 - Visibility: 20 statute miles - Lowest ceiling: none - Temperature: 10 °F ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 19971020033509I](https://openairdocs.org/incident/19971020033509I), Oct 20, 1997: Cessna 208B, Kasigluk, AK. Narrative: on October 20, 1997, about 1030 Alaska daylight time, the pilot of a Cessna 208B, N9304F, experienced a jammed aileron during the landing approach… From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.