# NTSB ANC98TA011: Bell 206B, N83146, Anchorage, AK, December 5, 1997 - Type: NTSB accident investigation - Classification: Accident · No injuries · Final report - Date: December 5, 1997, 11:20 local (15:20 UTC) - Place: Anchorage, AK - Coordinates: 61.159164, -149.990737 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=61.1592&lon=-149.9907&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report November 6, 1998 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 3173 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC98TA011 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/3173/pdf - Page: https://openairdocs.org/ntsb/ANC98TA011 ## Probable cause The pilot's failure to maintain adequate rotor RPM during an autorotation landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Hard landing, landing - flare/touchdown - autorotation - performed, pilot in command - rotor rpm - not maintained, pilot in command (cause) - misc rotorcraft,main rotor/tail boom contact - blade strike ## Analysis Two commercial pilots were practicing touchdown autorotation landings at a private snow covered airstrip. The purpose of the flight was for both pilots to maintain their proficiency. The first pilot had performed several straight-in touchdown autorotations. During the last autorotation, the first pilot entered the autorotation at 800 feet above the ground and about 80 knots. During the descent, the pilot maintained a 65 knot airspeed, and began a deceleration flare about 50 to 60 feet above the ground. As the ground speed dissipated, the pilot leveled the helicopter, applied main rotor collective pitch, and touched down with about a 30 foot ground run. As the helicopter slowed to a stop, the pilot indicated the helicopter shuddered several times. The main rotor blades struck the tail boom, severing the horizontal and vertical stabilizer, and the tail rotor assembly, from the tail boom. ## Factual narrative On December 5, 1997, about 1120 Alaska standard time, a Bell 206B helicopter, N83146, sustained substantial damage during a practice autorotation landing at the Campbell Airstrip, Anchorage, Alaska. The helicopter was being operated as a visual flight rules (VFR) local area government proficiency flight under Title 14 CFR Part 91, when the accident occurred. The helicopter is registered to, and operated by, the State of Alaska. The first pilot, seated in the right seat, and the second pilot, seated in the left seat, both certificated commercial pilots, were not injured. Visual meteorological conditions prevailed. The flight originated at Merrill Field, Anchorage, Alaska, at 1030. The first pilot, a Fish and Wildlife Protection Officer, and the second pilot, a pilot for the Alaska State Troopers, reported they were performing practice touchdown autorotation landings to maintain their proficiency. The first pilot had performed several, straight-in, touchdown autorotations to snow covered terrain. During the last autorotation, the first pilot entered the autorotation at 800 feet above the ground, and about 80 knots. He indicated during the descent he maintained a 65 knot airspeed, and began a deceleration flare about 50 to 60 feet above the ground. As the ground speed dissipated, the pilot leveled the helicopter, applied main rotor collective pitch, and touched down with about a 30 foot ground run. As the helicopter slowed to a stop, the pilot indicated the helicopter shuddered several times. Examination of the helicopter after landing revealed the main rotor blades struck the tail boom. The tail assembly, consisting of the horizontal and vertical stabilizer, and the tail rotor assembly, was severed from the tail boom. ## Aircraft - Registration: [N83146](https://openairdocs.org/deregistered/N83146-2007-06-12), registration cancelled 2007-06-12, S/N 1034, built 1973 (OpenAirDocs) - Reported make and model: Bell 206B - Registry model: [Bell 206B](https://openairdocs.org/model/bell-206b) (registry code 1181511) (OpenAirDocs) - Registry engine: [Allison 250 SER 400HP](https://openairdocs.org/engine/allison-250-ser-400hp) (registry code 03013, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 1034 - Airframe hours: 12638 - Engines: Allison 250-C20 400 horsepower turbo shaft - Damage: Substantial damage - Flight: Part 91 - Registered owner: State Of Alaska - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, September 9, 1997, 94 hours before - Departed: MRI, AK - Airport: CSR, Campbell Airstrip, runway 20, 5,000 × 150 ft, gravel ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 32; commercial; instrument ratings: helicopter; medical: class 2, valid medical--no waivers/lim.; seat: right; flight hours: 625 total, 3 in this make and model, 188 as pilot in command, 3 in the last 90 days, 3 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 5 statute miles - Lowest ceiling: none - Temperature: 19 °F ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 19971205037519A](https://openairdocs.org/incident/19971205037519A), Dec 5, 1997: Bell 206B, Anchorage, AK, Substantial damage. Practice autorotation. Pulled collective too soon. Hard landing. Main rotors chopped tailboom. (.4) two commercial pilots were practicing touchdown… From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.