# NTSB ANC98LA101: Piper PA-28-140, N1793J, Bethel, AK, July 18, 1998 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: July 17, 1998, 21:00 local (Jul 18, 1998, 05:00 UTC) - Place: Bethel, AK - Coordinates: 60.810592, -161.849182 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=60.8106&lon=-161.8492&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 4 minor - Status: Completed, report May 19, 1999 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 43069 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC98LA101 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/43069/pdf - Page: https://openairdocs.org/ntsb/ANC98LA101 ## Probable cause The fracture of the flap handle position locking pin, which resulted in an uncommanded raising of the flaps during takeoff. A factor was the pilot's decision to takeoff with a suspected problem in the flap system. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, takeoff - initial climb - operation with known deficiencies in equipment - intentional, pilot in command (contributing factor) - flight control,flap attachment - fractured (cause) - Altitude deviation,uncontrolled, takeoff - initial climb - flight control,flap - uncommanded (cause) - raising of flaps - inadvertent (cause) - climb - not possible, pilot in command - In flight collision with object, takeoff - initial climb - object - tree(s) ## Analysis The pilot experienced binding in the flaps during landing. Unable to find a problem, he decided to takeoff on his return flight. During initial climb, the manually operated flaps abruptly retracted. The pilot was unable to hold the flaps in the extended position to climb, and the airplane contacted trees located in the departure path. Investigation revealed that the flap position locking pin, part number 480-715 (59-040-187-1500), had fallen from its hole, but the retaining roll pin was still in place. The only way to remove this pin from the hole is to first remove the retaining pin, or fracture it in two pieces. The missing pin was not recovered, but a photograph shows a similar dimensioned pin lying below the flap handle assembly. ## Factual narrative On July 17, 1998, about 2100 Alaska daylight time, a Piper PA-28-140 airplane, N1793J, was destroyed when it collided with trees during takeoff from an off airport landing site approximately 72 miles east-southeast of Bethel, Alaska, at position 60 degrees 01 minutes North latitude, 160 degrees 11 minutes West longitude. The private pilot and the three occupants sustained minor injuries. The flight was conducted under 14 CFR Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident, and a flight plan was filed with a relative. The flight was departing the landing site on a return leg to Bethel. The pilot told the NTSB investigator on July 19, 1998, that during his landing at the site, the mechanical flap handle jammed in the flaps extended position, and could not be retracted. After landing, the pilot was able to retract the flaps and could not find a discrepancy. During the subsequent takeoff, while climbing through 25 feet agl, the flap handle fell to the retracted position, and the airplane began to descend. The pilot said that he again extended the flaps, but they would not lock in place. The airplane did not have room remaining to land, and collided with trees located in the takeoff path. The four occupants escaped from the airplane, which was then consumed by a postcrash fire. Subsequent inspection of the flap handle revealed the flap locking pin, part number 480-715 (59-040-187-1500), was not located in the flap handle assembly. Loss of this locking pin will result in air loads driving the flaps to the retracted position. The retaining roll pin, part number 480-733, was visible in the hole where the locking pin should have been. This roll pin installs through a drilled pilot hole in the locking pin. In order to remove the locking pin, either the roll pin must be removed, or the locking pin must fracture into two pieces. The airplane was cut into sections during recovery, and the missing locking pin was not found. Examination of photographs taken before recovery show what appears to be a metal pin of approximately the same dimensions as the missing locking pin lying beneath the flap handle assembly. Review of SDR records show three other cases of the locking pin fracturing and falling free of the flap handle. Early model PA-28 series airplanes used a 3/16 inch diameter pin; later model PA-28 series airplanes used a 1/4 inch pin. The accident airplane was manufactured with the smaller pin. No Service Bulletins or Airworthiness Directives apply to the locking pin, part number 480-715. ## Aircraft - Registration: [N1793J](https://openairdocs.org/deregistered/N1793J-1999-09-27), registration cancelled 1999-09-27, S/N 28-24219 (OpenAirDocs) - Reported make and model: Piper PA-28-140 - Registry model: [Piper PA-28-140](https://openairdocs.org/model/piper-pa-28-140) (registry code 7102802) (OpenAirDocs) - Category: Airplane - Serial number: 28-24219 - Airframe hours: 2905 - Engines: Lycoming O-320-D2A 160 horsepower reciprocating - Damage: Destroyed - Fire: On-Ground - Flight: Personal, Part 91 - Registered owner: Brandon T. Leary - Airworthiness certificate: Standard, Normal - Last inspection: Annual, August 29, 1997, 78 hours before - Departed: CANYON CREEK, AK - Destination: BET, AK ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 29; private; airplane ratings: single-engine land; medical: class 3, valid medical--no waivers/lim.; seat: left; flight hours: 291 total, 212 in this make and model, 243 as pilot in command, 25 in the last 90 days, 9 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 90° at 4 knots - Visibility: 40 statute miles - 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 19980717025609A](https://openairdocs.org/incident/19980717025609A), Jul 17, 1998: Piper PA28140, Bethel, AK, Destroyed. (There were no remarks here from the .19 when the .4 remarks were entered by tf on 12/28/99.) (From .4) the pilot experienced binding in the flaps during… ## Other investigations on N1793J (1) 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. - [NTSB NYC69D0406](https://openairdocs.org/ntsb/NYC69D0406), May 3, 1969: Piper PA-28 (N1793J), Mt Pocono, PA, substantial damage 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.