LAX99LA181 · Piper PA-31-310
Piper PA-31-310 · Accident en route
From Brackett Field (POC) to an unrecorded destination
Event
- NTSB case
- LAX99LA181
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Piper PA-31-310
- Aircraft type
- Piper PA-31
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N57AS
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Brackett Field (POC)To not recorded
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · climb to cruise
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Miscellaneous/other
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Company maintenance personnel › Maintenance, installation, inadequate
- Cooling system, cowling › Not secured
- Pilot in command › Aircraft preflight, inadequate
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The aircraft had been in maintenance for an adjustment to the right engine manifold pressure differential controller. The procedure required the uncowling of the engine. A certificated airframe and powerplant mechanic removed the cowling and made the required adjustments, then left for the day. A noncertificated mechanic replaced the cowling and the pilot then proceeded to perform the postmaintenance test flight. During climbout, the right engine upper cowling separated and wrapped around the right horizontal stabilizer. The pilot experienced difficulty in controlling the aircraft until the airspeed was reduced, then he returned to the airport and landed. Inspection of the cowling disclosed that the inboard latches on the upper cowling were not damaged. In his written statement, the pilot notes that his failure to detect the unlatched inboard cowling fasteners resulted from 'poor preflight inspection habits and a failure to follow the checklist.'
Probable cause
The in-flight separation of the right engine cowling due to the operator's inadequate maintenance quality control procedures and the pilot's inadequate preflight inspection.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX99LA181
- Event ID
- 20001205X00512
- Case number
- LAX99LA181
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 0c4a4195ee783ae260899b6cd190a1c2a10c502c9d5486ee6ab78138708ed82d; retrieved 2026-09-22T15:27:38.138Z.