Monday, August 6, 2018

Short Brothers SD3-60 Sherpa, registered to and operated by United States Department of Agriculture (USDA) as a public aircraft in support of the Forest Service, N148Z: Incident occurred October 13, 2016 at Missoula International Airport (KMSO), Montana

The National Transportation Safety Board did not travel to the scene of this incident.

Additional Participating Entity:

Federal Aviation Administration / Flight Standards District Office; Helena, Montana

Aviation Incident Factual Report - National Transportation Safety Board: https://app.ntsb.gov/pdf


Investigation Docket - National Transportation Safety Board: https://dms.ntsb.gov/pubdms


http://registry.faa.gov/N148Z  


Location: Missoula, MT
Incident Number: WPR17IA007
Date & Time: 10/13/2016, 1645 MDT
Registration: N148Z
Aircraft: SHORT BROS SD3 60 SHERPA
Aircraft Damage: Minor
Defining Event: Sys/Comp malf/fail (non-power)
Injuries: 2 None
Flight Conducted Under: Public Aircraft 

On October 13, 2016, about 1645 mountain daylight time, a Short Bros SD3-60 Sherpa airplane, N148Z, sustained minor damage following a nose gear collapse during landing, at the Missoula International Airport (MSO) Missoula, Montana. The two airline transport pilots, were not injured. The airplane was registered to and operated by United States Department of Agriculture (USDA), as a public aircraft in support of the Forest Service. Visual meteorological conditions prevailed and a visual flight rules (VFR) flight plan was filed for the ferry flight which originated from Kingman Airport, Kingman, Arizona, about 1253.

The pilots reported that prior to landing, they had an unsafe nose gear indication. After multiple unsuccessful attempts to get the nose gear to extend and indicate that it was down and locked, they decided to come in for a landing. During the landing roll, as the airplane's nose was lowered, the nose gear collapsed, and the forward section of the bottom of the fuselage, made contact with the runway surface. Once the airplane came to a stop, both pilots egressed.

Examination of the airplane by the operator revealed minor damage on the underside of the fuselage.

The airplane was returning to MSO, on its first flight, after being re-painted by a vendor in Kingman, Arizona. According to the operator, examination of the nose gear revealed that it failed to lock in the extended position and collapsed during landing. The flight crew attempted to extend and lock the nose gear during the flight but were unsuccessful.

Post incident examination of the nose gear down-lock actuator piston (plunger), revealed that its chrome surface had been painted, which resulted in the locking piston not engaging, and prevented the locking of the nose gear during landing gear extension. The painting of the nose gear down-lock actuator piston was not observed by maintenance personnel or the flight crew on their pre-flight exterior checks.

The airplane manufacturer Shorts issued a SD3-60 Sherpa Service Information Letter (SIL) Sherpa L-23, in April 2007, titled: Servicing/Painting – Removal of masking material/paint from nose landing gear down-lock actuator piston after cleaning/painting operations. The SIL described a similar incident where the nose gear failed to lock in the down position, on the first flight after the airplane had been re-painted. The subsequent investigation revealed paint spray on the exposed chrome piston of the nose landing gear down-lock actuator. The SIL stated "to 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 pre-flight checks to indicate below the specified pressure. The accumulator was serviced by maintenance to an adequate pressure, prior to takeoff. However, the pressure bled down during the incident flight, and when the emergency landing gear extension was used, the accumulator did not have adequate pressure. According to the operator's maintenance inspector, when activated, a fully serviced emergency accumulator forces the rapid application of hydraulic pressure into the system, however, according to the airplane's manufacturer, this is reliant on the main system hydraulic pressure being depleted so that the emergency pressure can change a control valve position. In this situation, the emergency pressure would be greater than the residual pressure of the failed main hydraulic system.

Pilot Information

Certificate: Airline Transport; Flight Instructor
Age: 58, Male
Airplane Rating(s): Multi-engine Land; Single-engine Land
Seat Occupied: Left
Other Aircraft Rating(s): Helicopter
Restraint Used: 4-point
Instrument Rating(s): Airplane; Helicopter
Second Pilot Present: Yes
Instructor Rating(s):  Airplane Multi-engine; Airplane Single-engine; Helicopter; Instrument Airplane; Instrument Helicopter
Toxicology Performed: No
Medical Certification: Class 2 With Waivers/Limitations
Last FAA Medical Exam: 11/12/2015
Occupational Pilot: Yes
Last Flight Review or Equivalent: 03/06/2015
Flight Time:   (Estimated) 8715 hours (Total, all aircraft), 148 hours (Total, this make and model), 7755 hours (Pilot In Command, all aircraft), 82 hours (Last 90 days, all aircraft), 12 hours (Last 30 days, all aircraft), 8 hours (Last 24 hours, all aircraft)

Co-Pilot Information

Certificate: Airline Transport; Flight Instructor; Commercial
Age: 49, Male 
Airplane Rating(s): Multi-engine Land; Single-engine Land
Seat Occupied: Right
Other Aircraft Rating(s): None
Restraint Used: 4-point
Instrument Rating(s): Airplane
Second Pilot Present: Yes
Instructor Rating(s): Airplane Multi-engine; Instrument Airplane
Toxicology Performed: No
Medical Certification: Class 2 Without Waivers/Limitations
Last FAA Medical Exam: 01/25/2016
Occupational Pilot: Yes
Last Flight Review or Equivalent: 03/02/2016
Flight Time:  (Estimated) 6424 hours (Total, all aircraft), 210 hours (Total, this make and model), 4921 hours (Pilot In Command, all aircraft), 90 hours (Last 90 days, all aircraft), 8 hours (Last 30 days, all aircraft), 8 hours (Last 24 hours, all aircraft) 

Aircraft and Owner/Operator Information

Aircraft Make: SHORT BROS
Registration: N148Z
Model/Series: SD3 60 SHERPA SHERPA VAR
Aircraft Category: Airplane
Year of Manufacture: 1994
Amateur Built: No
Airworthiness Certificate:
Serial Number: SH3428
Landing Gear Type: Hull; Tricycle
Seats:
Date/Type of Last Inspection: 06/24/2016, Condition
Certified Max Gross Wt.:
Time Since Last Inspection:
Engines:  2 Turbo Prop
Airframe Total Time: 5203.6 Hours at time of accident
Engine Manufacturer: Pratt & Whitney
ELT: C91  installed, not activated
Engine Model/Series: PT6A-65R
Registered Owner: USDA Forest Service
Rated Power: 1298 hp
Operator: USDA Forest Service
Operating Certificate(s) Held: None

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: MSO, 3206 ft msl
Distance from Accident Site: 0 Nautical Miles
Observation Time: 1653 MDT
Direction from Accident Site: 0°
Lowest Cloud Condition:
Visibility:  10 Miles
Lowest Ceiling: Overcast / 7000 ft agl
Visibility (RVR):
Wind Speed/Gusts: 6 knots /
Turbulence Type Forecast/Actual: / None
Wind Direction: 360°
Turbulence Severity Forecast/Actual: /
Altimeter Setting: 29.8 inches Hg
Temperature/Dew Point: 8°C / 1°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: KINGMAN, AZ (IGM)
Type of Flight Plan Filed: VFR
Destination: MISSOULA, MT (MSO)
Type of Clearance: Unknown
Departure Time: 1253 MST
Type of Airspace: Class D

Airport Information

Airport: MISSOULA INTL (MSO)
Runway Surface Type: Asphalt
Airport Elevation: 3206 ft
Runway Surface Condition: Dry
Runway Used: 29
IFR Approach: None
Runway Length/Width: 9501 ft / 150 ft
VFR Approach/Landing: Full Stop

Wreckage and Impact Information

Crew Injuries: 2 None
Aircraft Damage: Minor
Passenger Injuries: N/A 
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 2 None
Latitude, Longitude: 46.916389, -114.090556 (est)

NTSB Identification: WPR17IA007
14 CFR Public Aircraft
Incident occurred Thursday, October 13, 2016 in Missoula, MT
Aircraft: SHORT BROS SD3 60 SHERPA, registration: N148Z
Injuries: 2 Uninjured.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

On October 13, 2016, about 1645 Mountain daylight time, a Short Bros SD3-60 Sherpa, N148Z, sustained minor damage following a nose gear collapse during landing, at the Missoula International Airport (MSO) Missoula, Montana. Two Airline Transport Pilots, the only occupants of the airplane, were not injured. The airplane was registered to and operated by United States Department of Agriculture (USDA), as a public use aircraft in support of the Forest Service. Visual meteorological conditions prevailed and a visual flight rules (VFR) flight plan was filed for the ferry flight which originated from Kingman Airport, Kingman, Arizona, about 1253 Mountain standard time.

The pilots reported that prior to landing, they had an unsafe nose gear indication. After multiple unsuccessful attempts to get the nose gear to extend and indicate that it was down and locked, they came in for a landing. During the landing roll, as the airplane's nose was lowered, the nose gear collapsed, and the forward section of the bottom of the fuselage, made contact with the runway surface. Once the airplane came to a stop, the flight crew egressed.

Examination of the airplane by the operator revealed that the underside of the fuselage, near the nose wheel, sustained minor damage.

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