CEN25LA093 · Robinson Helicopter R22 BETA
Robinson Helicopter R22 BETA · Accident: powerplant system/component malfunction/failure while maneuvering
From Pampa, TX to an unrecorded destination
Event
- NTSB case
- CEN25LA093
- 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
Robinson Helicopter R22 BETA
- Aircraft type
- Robinson R22
- Category
- Helicopter
- 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
- N7191B
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Pampa, TXTo not recorded
- Aircraft age
- About 25 years (built 2000)
- 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
- Maneuvering · low-altitude flying
- 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
- Powerplant system/component malfunction/failure
- Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
- Tree(s)
- 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
- Personnel issues › Task performance
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot reported that, while performing an aerial inspection of a fence, he heard a loud bang come from the engine and the helicopter began to shake and lose altitude. The shaking stopped momentarily but then started again and the engine lost total power. The pilot performed a forced landing, during which the helicopter impacted cedar trees and then rolled several times down a hill. The helicopter sustained substantial damage to the fuselage, tail boom, and main rotor gearbox. A postaccident inspection of the engine revealed that the No. 3 cylinder intake valve head was burned and chipped specifically on the combustion face, margin, and seat face. Additionally, the bolts that secured the intake manifold system to the engine block were loose. A review of maintenance records revealed that all four engine cylinders were removed for overhaul and reinstalled about 8 months before the accident due to low compression. According to the pilot, who was also the owner of the helicopter, about one month before the accident (about 360 hours after the cylinders were overhauled), the No. 1 cylinder was replaced due to the intake valve head being burned. According the engine manufacturer, when engine cylinders are removed and/or reinstalled, the bolts that secure the intake manifold system to the engine block need to be removed to manipulate the cylinders. It is likely that when the cylinders were removed 8 months before the accident for overhaul and reinstallation, the bolts that secured the intake manifold system to the engine block were not properly torqued when the cylinders were reinstalled. The loose intake manifold system likely allowed unmetered air into the engine, resulting in an overly lean fuel/air mixture, which resulted in damage to both the No. 1 and No. 3 cylinder intake valves. The damage to the valves would likely result in poor combustion and a decrease in engine performance.
Probable cause
Improperly torqued intake manifold bolts that allowed unmetered air to enter the engine, resulting in an overly lean fuel-air mixture, eventual failure of the No. 3 cylinder intake valve, and a total loss of engine power.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN25LA093
- Event ID
- 20250210199672
- Case number
- CEN25LA093
- 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: 273615edc080e43731bf1ee8c6d2187d7c274a7a4fd5c3541f8ab896fa26d6ee; retrieved 2026-09-16T19:38:57.457Z.