CEN21LA386 · Acro Sport II
Acro Sport II · Accident: fuel exhaustion en route
From Indianapolis Metropolitan Airport (UMP) to Indianapolis Metropolitan Airport (UMP)
Event
- NTSB case
- CEN21LA386
- 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
Acro Sport II
- Aircraft type
- Acro Sport II
- 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
- N169BF
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Indianapolis Metropolitan Airport (UMP), Fishers, INTo Indianapolis Metropolitan Airport (UMP), Fishers, IN
- Aircraft age
- About 26 years (built 1995)
- 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 · cruise
- 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 exhaustion
- 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 power plant
- Aircraft › Aircraft systems
- Aircraft › Fluids/miscellaneous hardware
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The pilot was conducting a post-maintenance flight in the experimental airplane to “break-in” two engine cylinders that were replaced on the day before the accident. The engine was operated at maximum speed with a full rich mixture setting throughout the flight. The pilot stated that the airplane lost total engine power about 1 hour after takeoff. During the forced landing, the airplane impacted a street signpost, resulting in substantial damage to a structural fuselage tube.
The pilot reported that the fuel tank contained 23 gallons of fuel at the start of the flight. Postaccident examination found that the airplane’s fuel tank was empty and that only 2 to 3 fluid ounces of fuel were recovered from the fuel system. Evidence of a fuel leak was found within the engine compartment and on the exterior lower fuselage skins aft of the firewall. Examination of the fuel system revealed that the fuel inlet fitting to the fuel control unit was finger tight.
In preparation for a postaccident engine test, the loose fuel inlet fitting was tightened, and the fuel system was pressurized to confirm that no other leak sources existed. The engine started and ran normally without any hesitation, stumbling, or interruption in power. There was no evidence of a fuel system leak following the engine run.
Based on data collected during the engine test, the fuel consumption rate at maximum engine power on the ground (static power) was about 13.69 gallons per hour (gph) at an engine speed of 2,260 rpm. The estimated fuel consumption rate while in flight at maximum engine power (2,800 rpm) was about 16.96 gph. With a full fuel tank (23 gallons) at departure, the airplane’s fuel endurance was about 1 hour 21 minutes if the engine was operated at maximum power with a full rich mixture setting.
Other than the loose fuel inlet fitting, the engine examination and test run revealed no mechanical malfunctions that would have prevented normal engine operation during the flight. Air traffic control radar data showed that the airplane was airborne for about 1 hour 15 minutes during the accident flight. Thus, it is likely that the loose fuel inlet fitting leaked fuel during the flight, which resulted in fuel exhaustion and the subsequent total loss of engine power.
Probable cause
The airplane’s total loss of engine power due to fuel exhaustion as a result of leaking fuel from a loose fuel inlet fitting to the fuel control unit.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN21LA386
- Event ID
- 20210826103760
- Case number
- CEN21LA386
- 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, coordinates, 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: 2e679a4173f2de91a007f54316f3aaa445b52025ee3f56590d058fcbeec34b9c; retrieved 2026-09-16T14:27:38.008Z.