WPR17IA007 · Short Bros SD3 60 SHERPA SHERPA VAR
USDA Forest Service Short Bros SD3 60 SHERPA SHERPA VAR · Incident: system/component malfunction/failure (non-power) on approach
From Kingman Airport (IGM) to Missoula Montana Airport (MSO)
Event
- NTSB case
- WPR17IA007
- 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
- Incident
- 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
- Government
- 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
Short Bros SD3 60 SHERPA SHERPA VAR
- Aircraft type
- Short Bros SD3
- 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
- N148Z
- Operator
- USDA Forest Service
- Onboard fatalities
- Unknown
- Route
- From Kingman Airport (IGM), Kingman, AZTo Missoula Montana Airport (MSO), Missoula, MT
- Aircraft age
- About 22 years (built 1994)
- 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
- Public Aircraft
- 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
- Approach
- 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
- System/component malfunction/failure (non-power)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Minor
Cause areas
- Aircraft › Aircraft systems
- Organizational issues › Support/oversight/monitoring
- Personnel issues › Action/decision
- Personnel issues › Task performance
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The airline transport pilots reported that, during a ferry flight of an airplane that had just had been repainted, while on approach at its destination, the nose gear extended but failed to lock and subsequently collapsed on landing.
Postaccident examination of the nose gear confirmed the nose gear's failure to lock, which led to its collapse. Observation of the nose gear down-lock actuator piston revealed that it had been painted, which prevented the piston from engaging and locking the nose gear during extension. Before the flight, maintenance personnel and the flight crew did not observe that the nose gear down-lock actuator piston area was painted.
The airplane manufacturer issued a Service Information Letter (SIL) in 2007, that described a similar incident where the nose gear failed to lock in the down position on the first flight after an airplane had been repainted. The subsequent investigation revealed paint spray on the exposed piston of the nose landing gear down-lock actuator. The SIL stated "ensure that all masking material has been removed from the exposed piston after cleaning/painting, and that the piston is free from any paint or cleaning materials."
Additionally, the landing gear emergency accumulator was observed during the preflight checks to be below the specified pressure. The accumulator was serviced to an adequate pressure prior to takeoff. Subsequently, the pressure bled down during the incident flight, and when the emergency landing gear extension was used by the flight crew, the accumulator did not have adequate pressure. According to the airplane manufacturer, the emergency landing gear extension is reliant on the main system pressure being depleted so that the emergency pressure can change a control valve position. Since the airplane's main hydraulic system was operative during the flight, the inability to use the landing gear emergency extension system, because of the lack of adequate pressure, would have been inconsequential, since the main system pressure was not depleted.
Probable cause
The failure of the nose landing gear down-lock piston to engage due to paint accumulation, which resulted in a nose landing gear collapse during landing. Also causal was the failure of the facility that performed the painting to comply with manufacturer guidance regarding painting of the airplane.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record WPR17IA007
- Event ID
- 20161014X31149
- Case number
- WPR17IA007
- 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. 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: d6604f8d7915bfcb5bc74a30bb0596d5df898269e950e377505d2deaf3bca010; retrieved 2026-09-16T04:23:57.742Z.