CEN16LA387 · Pahnke Vernon A VANS RV 9A
Pahnke Vernon A VANS RV 9A · Accident: loss of engine power (partial) en route
From Bolingbrook's Clow International Airport (1C5) to Gardner Municipal Airport (K34)
Event
- NTSB case
- CEN16LA387
- 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
- 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
Pahnke Vernon A VANS RV 9A
- Aircraft type
- Pahnke Vernon VANS RV 9A
- 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
- N699RV
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Bolingbrook's Clow International Airport (1C5), Bolingbrook, ILTo Gardner Municipal Airport (K34), Gardner, KS
- Aircraft age
- About 10 years (built 2006)
- 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
- 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
- Loss of engine power (partial)
- 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
- Personnel issues › Task performance
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot was conducting a cross-country flight in an experimental airplane when he observed the fuel pressure fluctuating, and the engine began to surge. The pilot turned on the backup fuel pump but the engine continued to surge, so he diverted to a nearby airport. The pilot stated that he had difficulty visually acquiring the airport and was losing altitude while circling over the airport. He performed an "S" turn but was still too high. He was running out of runway below him, so he performed a "hard slip" to lose altitude. The airplane stalled 10-15 ft above the runway, hit the ground, and slid about 30 ft before stopping.
The primary fuel pump had failed 4 days before the accident. The pilot replaced the fuel pump with a new unit that required partial assembly. He noted during assembly that there was not an O-ring where the lower fitting attached but that the mating surfaces were different between the two pumps and he had believed one was not required. The instructions with the new pump did not address the installation of an O-ring at the fitting.
After the accident, the pilot reexamined the box the new fuel pump came in and found an O-ring for the lower fitting. Without the O-ring installed, the fuel system was not able to maintain the fuel pressure necessary to ensure smooth engine operation and resulted in the partial loss of engine power. The pilot stated the accident resulted from this maintenance issue.
Probable cause
The pilot's failure to properly assemble the fuel pump, which resulted in the loss of fuel pressure and the subsequent partial loss of engine power.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN16LA387
- Event ID
- 20160930X54139
- Case number
- CEN16LA387
- 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. 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: c05c6586fe6bbed2424f1a4ff947fea04d7557330850a90d2b01345ec00700e2; retrieved 2026-09-16T04:20:11.514Z.