CEN21LA242 · Piper J4A
Piper J4A · Accident: fuel related during takeoff
Event
- NTSB case
- CEN21LA242
- 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
- Event fatalities
- Unknown
- Ground fatalities
- Unknown
- 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 J4A
- Aircraft type
- Piper J4
- 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
- N8501Z
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From not recordedTo not recorded
- Aircraft age
- About 81 years (built 1940)
- 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
- Takeoff
- Defining eventThe 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
- Fuel related
- 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
- Aircraft › Aircraft systems
- Personnel issues › Task performance
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
During takeoff, the airplane traveled about three-quarters of the way down the runway and climbed to about 300 ft above ground level. The engine sputtered once and stopped producing power. The pilot switched the fuel selector from the forward fuel tank to the auxiliary fuel tank and unsuccessfully tried to restart the engine. The pilot maneuvered the airplane for a forced landing, and the airplane impacted the ground. The pilot reported that fuel was pouring into the cockpit after the airplane came to rest, and he quickly exited the airplane. The airplane sustained substantial damage to both wings and the fuselage.
A postaccident examination revealed that the forward fuel tank cap was not the correct part for the airplane; the cap had an unknown part number etched on it with no manufacturer name displayed. The fuel tank cap appeared to be manufactured with a single vent hole and was equipped with two worn gaskets stacked under the cap. The lower gasket had multiple visible cracks present on both sides of it. The upper gasket was wrinkled and was displaced toward the vent hole, which blocked the venting capability of the fuel tank. For the accident model airplane, the sole source of venting for the forward fuel tank was through a vented fuel tank cap.
The pilot reported that the forward fuel tank cap was on the airplane when he purchased it several years ago. The pilot did not have any knowledge of the origin or the background of the forward fuel tank cap.
It is likely the engine sustained fuel starvation during the takeoff due to blockage of the forward fuel tank cap vent hole. Based on the available evidence, it could not be determined when the vent hole became blocked. The accident occurred 39 days and 2.3 flight hours after the most recent annual inspection. During the inspection, the mechanic should have observed the multiple visible cracks present on both sides of the lower gasket in the fuel tank cap. Further, during the preflight inspection, the pilot should have observed the multiple visible cracks present on both sides of the lower gasket in the fuel tank cap. Had the deficiencies with the fuel tank cap gasket been observed during the annual inspection or preflight, it is likely the fuel tank cap would have been replaced.
Probable cause
A total loss of engine power due to a blocked fuel tank cap vent hole, which resulted in fuel starvation. Contributing to the accident was the mechanic’s and the pilot’s inadequate inspections of the fuel tank cap.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN21LA242
- Event ID
- 20210601103179
- Case number
- CEN21LA242
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
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, cause areas. 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: aa08ebe29f4c0ad123a57f2ea15820d2ee9e00706ba90a0f1795472cbbefc626; retrieved 2026-09-16T14:06:24.840Z.