# NTSB FTW99LA105: Bell 206L-1, N255AL, Shawnee, OK, April 5, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 5, 1999, 10:00 local (15:00 UTC) - Place: Shawnee, OK - Coordinates: 35.32973, -96.909088 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.3297&lon=-96.9091&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 6 uninjured - Status: Completed, report June 22, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 46073 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW99LA105 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46073/pdf - Page: https://openairdocs.org/ntsb/FTW99LA105 ## Probable cause The improper flare during an autorotation by the pilot-in-command. A factor was the loss of engine power for an undetermined reason. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, cruise - reason for occurrence undetermined (contributing factor) - Forced landing, emergency landing after takeoff - autorotation - initiated, pilot in command - Hard landing, emergency descent/landing - flare - improper, pilot in command (cause) - misc rotorcraft,main rotor/tail boom contact ## Analysis The main rotor blades struck and severed the tailboom of the helicopter during a hard landing following a loss of engine power. The helicopter departed the airport to the southwest and climbed to 400 feet AGL. The pilot turned the helicopter downwind and leveled the aircraft. He set 'cruise power' and the engine 'spooled down.' The pilot performed an autorotation to a muddy, grassy field and landed hard. The engine was test run and it was determined that the fuel scheduling was incorrect as the turbine outlet temperature would exceed the maximum allowed. After replacement of the fuel control unit, the engine was 'found to meet new engine performance at all guarantee test points.' The fuel control unit was functionally tested and operated within service limits. The reason for the loss of engine power could not be determined. ## Factual narrative On April 5, 1999, at approximately 1000 central daylight time, a Bell 206L-1 helicopter, N255AL, was substantially damaged during a forced landing following a loss of engine power during takeoff near Shawnee, Oklahoma. The instrument rated commercial pilot and five passengers were not injured. The helicopter was registered to and operated by Air Flite Inc., of Seminole, Oklahoma. Visual meteorological conditions prevailed for the Title 14 Code of Federal Regulations Part 135 on-demand air taxi flight and a flight plan was not filed. The aerial observation flight was originating at the time of the accident. According to the 7,500-hour pilot, the purpose of the flight was to provide a tour of the city to local politicians. The helicopter departed the airport to the southwest and climbed to 400 feet agl. He turned the helicopter downwind and leveled the helicopter. The pilot stated the he set "cruise power" and "the engine spooled down." He turned the helicopter into the wind as he initiated an autorotation to an open field. During the flare/touchdown sequence of the autorotation, the main rotor blades struck and severed the tailboom. The helicopter came to rest upright in a grassy, muddy field one mile from the airport. The pilot added that the engine continued to run at ground idle speed upon completion of the autorotation. An FAA inspector who visited the accident site reported that fuel was present "from the aircraft firewall to the fuel pump." The pilot reported that at the time of the accident, the winds were from 230 degrees at 30 knots, gusting to 35 knots. The 435-horsepower Allison A250-C28B turboshaft engine had accumulated 5,411.4 hours since new, 1,159.4 hours since its last overhaul, and 1.5 hours since the last annual inspection. On April 14, 1999, the engine was examined under the supervision of an FAA inspector at Dallas Airmotive Inc., of Dallas, Texas. The pneumatic system was tested and no leakage was observed. The engine was placed in a test cell and started. During two timed "snap acceleration[s] from flight auto to takeoff, the fail safe temperature limit on the test stand was tripped causing the engine to shut down." It was determined that fuel scheduling was incorrect. The Allied Signal/Bendix fuel control unit (model DP-T3, p/n 2524738-34) was replaced with a slave fuel control unit, provided by Dallas Airmotive. According to the engine manufacturer, "the engine was [then] found to meet new engine performance at all guarantee test points." The fuel control unit was functionally tested under the supervision of an FAA inspector at the Allied Signal Aerospace facilities in Burbank, California. The functional test revealed that the unit operated within service limits. According to the manufacturer, no anomalies were found that would have "prohibited it from operating normally" at the time of the accident. ## Aircraft - Registration: N255AL (not matched to a registry record) - Reported make and model: Bell 206L-1 - Category: Helicopter - Serial number: 45602 - Airframe hours: 5563 - Engines: Allison C250-28B 435 horsepower turbo shaft - Damage: Substantial damage - Flight: Part 135 - Registered owner: Air Flite Inc. - Airworthiness certificate: Standard, Normal - Last inspection: Annual, March 29, 1999, 2 hours before - Departed: SNL, OK ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 40; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: right; flight hours: 7,500 total, 3,800 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 230° at 30 knots, gusting 35 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 61 °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 19990405017709A](https://openairdocs.org/incident/19990405017709A), Apr 5, 1999: Bell 206L1, Shawnee, OK, Substantial damage. (.19) On April 5, 1999, at approximately 1000 central daylight time, a Bell 206L1 helicopter, N255AL, was substantially damaged during a forced landing… 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.