# NTSB ANC94LA068: Maule M6-235, N56447, Bethel, AK, June 6, 1994 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: June 6, 1994, 14:00 local (22:00 UTC) - Place: Bethel, AK - Coordinates: 60.809307, -161.85025 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=60.8093&lon=-161.8502&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report April 25, 1995 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 2512 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC94LA068 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/2512/pdf - Page: https://openairdocs.org/ntsb/ANC94LA068 ## Probable cause THE PILOT'S FAILURE TO MAINTAIN DIRECTIONAL CONTROL DURING LANDING. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - on ground/water, landing - roll - directional control - not maintained, pilot in command (cause) - ground loop/swerve - inadvertent, pilot in command - landing gear,axle - overload ## Analysis ACCORDING TO THE PILOT'S ATTORNEY, AFTER LANDING THE RIGHT MAIN WHEEL BEGAN TO 'DRAG', AND THE AIRPLANE VEERED TO THE RIGHT. THE PILOT WAS NOT ABLE TO CONTROL THE TURN AND THE AIRPLANE GROUND LOOPED. EXAMINATION OF THE AIRPLANE SHOWED THAT THE RIGHT AXLE HAD FRACTURED AND WAS BENT UPWARD. SUBSEQUENT VISUAL EXAMINATION OF THE AXLE SHOWED NO FATIGUE STRIATIONS VISIBLE ON THE FRACTURE SURFACES. THE FRACTURE SURFACE EXHIBITED CHARACTERISTICS OF OVERLOAD FAILURE. ## Factual narrative On June 6, 1994, at approximately 1400 Alaska daylight time, a wheel equipped Maule M6-235 airplane, N56447, registered to and operated by the Pilot, ground looped while trying to land at the Bethel airport, Bethel, Alaska. The personal flight, operating under 14 CFR Part 91, departed Manokotak, Alaska, and the destination was Bethel. The commercial certificated pilot and the one passenger were not injured. The airplane received substantial damage. Visual meteorological conditions prevailed. According to information provided by the Pilot's attorney, the pilot landed the airplane on runway 36 at Bethel and during the landing roll the right main wheel began to "drag." The airplane then veered to the right. The Pilot was not able to control the turn and the airplane ground looped. According to the attorney, the pilot examined the airplane on the site and stated that the right main gear wheel axle failed which caused the airplane to veer to the right. The gear leg and axle were submitted for examination. The parts were examined by two Safety Board Investigators. The axle was still attached to the main gear leg and was bent upward at a 10 to 12 degree angle. The fracture on the axle occurred directly inside a ring which was spot welded to the axle in six locations along the circumference. This ring is the mounting plate for the brake caliper. The axle was removed from the gear leg by continuous bending until failure and the surfaces were examined with a 10x glass. The general landscape of the fracture surface was typical of overload failure depicted by the 45 degree angles along the fracture's surfaces. Most of the surface area was discolored and had a light orange rust appearance. The rust did not scale off the surface. One portion of the fracture surface was bright in appearance and measured approximately 3/16 of an inch along the axle's circumference. This was the area of the axle that had remained attached to the main gear leg and was failed by the investigators. There were no visible fatigue striations on the discolored fracture surfaces. According to Brian Cox, mechanic for Flight Safety Alaska, they accomplished an annual inspection on the airplane. He stated that during the initial taxi he noticed that the right brake was spongy. He also noticed that the airplane was equipped with GAR AERO wheels. This wheel had the tire bead bolted to the wheel rim to keep the wheel from turning on the rim. He stated that both main gear wheel bearings were serviced and turned freely. The right brake was serviced by adding fluid and bleeding the brake. The left brake was not serviced. Mr. Cox stated that the taxi after the annual was normal and the brakes felt normal. He stated the Pilot flew the airplane around the traffic pattern after the annual inspection. Examination of the airplane after the accident, by Bethel Aircraft, Bethel, Alaska, showed that the right main gear brake assembly was properly installed and was not "dragging." The right wheel rotated freely but due to the upward bent axle the bolt heads that held the tire bead to the rim would strike the gear leg. According to a polaroid photograph submitted by the Pilot's attorney, the right main gear is aligned with a curved skid mark which starts in the center of the photograph and curves to the right and ends at the right main tire. ## Aircraft - Registration: [N56447](https://openairdocs.org/aircraft/N56447), registered now, S/N 7383C, built 1981 (OpenAirDocs) - Reported make and model: MAULE M6-235 - Registry model: [Maule M-6-235](https://openairdocs.org/model/maule-m-6-235) (registry code 5460160) (OpenAirDocs) - Registry engine: [Lycoming IO-540 series](https://openairdocs.org/engine/lycoming-io-540-series) (registry code 41530, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 738C - Airframe hours: 1700 - Engines: Lycoming IO-540 235 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Robertson, James - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 1, 1994, 10 hours before - Departed: 17Z, MANOKOTAK, AK - Airport: BET, Bethel, runway 36, 6,398 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 75; commercial; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 4,900 total, 1,700 in this make and model, 4,860 as pilot in command, 23 in the last 30 days, 7 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 260° at 11 knots - Visibility: 50 statute miles - Lowest ceiling: none - Temperature: 55 °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). - [Accident 19940606013979A](https://openairdocs.org/incident/19940606013979A), Jun 6, 1994: Maule M6235, Bethel, AK, Substantial damage. Right main gear axle failed on landing causing ground loop. Axle bent on prior overstress. Rim lugs striking axle. 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.