Thursday, February 06, 2020

System/Component Malfunction/Failure (Non-Power): Beech 99A Airliner, N326CA; accident occurred January 19, 2017 at Billings Logan International Airport (KBIL), Billings, Yellowstone County, Montana

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

Additional Participating Entity:

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

Aviation Accident Factual Report - National Transportation Safety Board:

Investigation Docket - National Transportation Safety Board:

Location: Billings, MT
Accident Number: WPR17LA056
Date & Time: 01/19/2017, 1148 MST
Registration: N326CA
Aircraft: BEECH 99
Aircraft Damage: Substantial
Defining Event: Sys/Comp malf/fail (non-power)
Injuries: 1 None
Flight Conducted Under: Part 135: Air Taxi & Commuter - Non-scheduled 

On January 19, 2017 about 1148 mountain standard time, a Beech 99A airplane, N326CA, experienced a landing gear collapse while landing at the Billings Logan International Airport, Billings, Montana. The commercial pilot was not injured; the airplane sustained substantial damage. The airplane was registered to and operated by Alpine Aviation Inc., d.b.a. Alpine Air, as a Title 14 Code of Federal Regulations Part 135 cargo transport flight. Visual meteorological conditions prevailed, and an instrument flight rules flight plan had been filed but was not activated. The flight departed from Dawson Community Airport, Glendive, Montana about 0945, with a planned destination of Sidney-Richland Municipal Airport, Sidney, Montana.

The pilot reported that after departure, he retracted the landing gear and heard a "thud" sound. The landing gear "unsafe" light was illuminated, and the left landing gear light remained illuminated green, an indication that it was still extended despite the landing gear handle being in the retracted position. When reaching his initial destination of Sidney, the pilot performed a low pass over the runway to enable maintenance personnel on the ground to do a visual assessment. A mechanic reported to the pilot that the nose gear was in trail. The pilot diverted to Billings and the air traffic control personnel confirmed observing the nose gear extended at a 450 angle.

The pilot further stated that he aligned with runway 28R and just prior to touch down, he feathered the propellers and decreased the airspeed. During touchdown, the right main landing gear collapsed, and the airplane came to rest on the centerline. As a result of the impact, the right aileron and right-wing spar was substantially damaged.

Pilot Information

Certificate: Commercial
Age: 25, Male
Airplane Rating(s): Multi-engine Land; Single-engine Land; Single-engine Sea
Seat Occupied: Left
Other Aircraft Rating(s): None
Restraint Used:
Instrument Rating(s): Airplane
Second Pilot Present: No
Instructor Rating(s): None
Toxicology Performed: No
Medical Certification: Class 2 Without Waivers/Limitations
Last FAA Medical Exam: 10/20/2016
Occupational Pilot: Yes
Last Flight Review or Equivalent: 09/17/2016
Flight Time:  1419 hours (Total, all aircraft), 270 hours (Total, this make and model), 1308 hours (Pilot In Command, all aircraft), 196 hours (Last 90 days, all aircraft), 57 hours (Last 30 days, all aircraft), 4 hours (Last 24 hours, all aircraft)

Aircraft and Owner/Operator Information

Aircraft Make: BEECH
Registration: N326CA
Model/Series: 99 A
Aircraft Category: Airplane
Year of Manufacture: 1970
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: U-135
Landing Gear Type: Retractable - Tricycle
Seats: 2
Date/Type of Last Inspection: 12/14/2016, AAIP
Certified Max Gross Wt.: 10900 lbs
Time Since Last Inspection: 96 Hours
Engines: 2 Turbo Prop
Airframe Total Time: 46422 Hours at time of accident
Engine Manufacturer: Pratt and Whitney
ELT: C126 installed, not activated
Engine Model/Series: PT6A-28
Registered Owner: Alpine Aviation Inc
Rated Power: 750 hp
Operator: Alpine Aviation Inc
Operating Certificate(s) Held: On-demand Air Taxi (135)
Operator Does Business As: Alpine Air
Operator Designator Code: TIMA

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: BIL
Distance from Accident Site: 0 Nautical Miles
Observation Time: 1853 UTC
Direction from Accident Site:
Lowest Cloud Condition: Clear
Visibility:  10 Miles
Lowest Ceiling: Broken / 10000 ft agl
Visibility (RVR):
Wind Speed/Gusts: 12 knots /
Turbulence Type Forecast/Actual: None / None
Wind Direction: 230°
Turbulence Severity Forecast/Actual: N/A / N/A
Altimeter Setting: 29.49 inches Hg
Temperature/Dew Point: 4°C / -6°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: GLENDIVE, MT (GDV)
Type of Flight Plan Filed: IFR
Destination: SIDNEY, MT (SDY)
Type of Clearance: None
Departure Time: 0945 MST
Type of Airspace:

Airport Information

Runway Surface Type: Asphalt
Airport Elevation: 3651 ft
Runway Surface Condition: Dry
Runway Used: 28R
IFR Approach: None
Runway Length/Width: 10518 ft / 150 ft
VFR Approach/Landing: Traffic Pattern 

Wreckage and Impact Information

Crew Injuries: 1 None
Aircraft Damage: Substantial
Passenger Injuries: N/A
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 1 None
Latitude, Longitude: 45.807778, -108.542778

Tests And Research

Post-accident examination of the left landing gear actuator, part number (p/n) 99-388-008-1, revealed that it appeared to be fractured allowing the hydraulic fluid to pass freely from the downside to the upside, prohibiting pressure to control the landing gear's hydraulic system. Based on the pilots' statements about the landing, the fractured left landing gear was shipped to Textron Aviation, the airframe manufacturer, for examination. The piston rod, p/n 4A125C4, was separated into two pieces through several threads. According to the report, the damaged threads displayed crack propagation by fatigue. The final fracture was by overload and resulted in deformation of the damaged threads.

The National Transportation Safety Board Materials Laboratory reviewed the Textron Aviation Materials report and pictures. The lab specialist reported that the fractography indicated that the piston rod failed in the threaded region by fatigue cracking over about 60% of the cross section due primarily to axial tension force. Contact wear was observed on the faying surface of the retaining nut, the shoulder of the piston rod, and on the faying surfaces of the piston head. These signatures were consistent with the nut not being tight enough to mitigate relative sliding of the piston head relative to the piston rod shoulder and the retaining nut. It could not be determined if the manufacturer required a specific torque to be applied to the nut during assembly.

The airplane operator reported that the airplane had amassed 46,416.3 hours of total time in service. According to the maintenance records, the left actuator was last overhauled in November 2001, at which time the piston rod was replaced. The operator further reported that the part had acquired 7,445.2 hours equating to 8,267 cycles. The Beechcraft Model 99 Series Maintenance Manual stated that the landing gear hydraulic actuators should be overhauled or replaced every 10,000 hours.


  1. 46,422 airframe time = Good aircraft for hauling mail and other goods.

  2. Pilot did a great job in a stressful situation. Congratulations.

  3. Manual soon to be edited to change overhaul of actuator to every 7,445 hours...

  4. Hard to believe it's been 3 years since this accident happened.