Piper PA-28-150 accident near Gila Bend, Arizona, November 12, 1998
On November 12, 1998 at about 8:00 pm local time, a Piper PA-28-150, registered N991PK, was substantially damaged in an accident near Gila Bend, Arizona. It was a personal flight under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The crankshaft gear attach bolt loosening and backing out of its crankshaft bore, which led to the fatigue failure of the crankshaft gear dowel pin due to excessive working of the gear. The sequence of failures was the result of the engine overhaul shop's failure to comply with an Airworthiness Directive and the engine manufacturer's Service Bulletin.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- November 12, 1998 · about 8:00 pm local time
- Place
- Gila Bend, Arizona · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Piper PA-28-150 · all PA-28-150s on the register
- Registration
- N991PK · no longer on the register · serial 28-2369
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot said that no engine discrepancies were noted during either the preflight or the initial cruise portion of the flight, and that all engine instrument readings were normal. Between 500 and 1,100 mean sea level, the engine suffered a significant loss of power accompanied by sputtering, vibration, and the rpm fluctuating. He declared an emergency, performed the emergency checklist with no changes, and made a forced landing on a road. During the landing rollout the airplane struck a road sign that he had not seen. Postaccident inspection of the engine revealed the gear at the back of the crankshaft was detached and moving freely between the corresponding gears. The crankshaft gear attaching bolt and threads were undamaged and the bolt appeared to have backed out of the crankshaft and was resting in the crankshaft gear bore. The bolt locking plate remained at the head of the bolt, and exhibited fretting signatures. Fretting signatures were also located around the mating surfaces of the gear and crankshaft bore. The crankshaft gear dowel pin had failed, with fatigue striations visible to the naked eye. An engine overhaul was completed 1 month after an airworthiness directive (AD) was published requiring inspection of the crankshaft gear and the bolt to prevent the bolt from backing out and liberating the crankshaft gear. No evidence of compliance with this AD was found in the engine maintenance records.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: private
- Ratings: single-engine land; instrument: airplane
- Flight time: 305 hours in all; 9 in this make and model; 1 in the last 90 days; 271 as pilot in command
- Medical certificate: Class 3 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 4,680 hours
- Last inspection: annual inspection, June 20, 1998; 30 hours since
- Maximum gross weight: 2,150 lb
- Seats: 4
- Landing gear: fixed
- Engine: Lycoming O-320-E2A (piston); 0 hours total
The flight
- Departed from: MYF San Diego CA at 6:00 pm
- Destination: PHX Phoenix AZ
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 300° at 5 knots
- Visibility: 50 statute miles
- Sky: scat at 5,000 ft
- Temperature: 64°F (18°C), dew point 43°F (6°C)
- Altimeter: 30.00 inHg
- Observation at 7:55 pm from GBN, 90 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.