# NTSB ANC20LA089: Eurocopter AS 350, N354PA, Fort Greely, AK, September 6, 2020 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: September 6, 2020, 09:05 local (17:05 UTC) - Place: Fort Greely, AK - Coordinates: 63.983339, -145.76679 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=63.9833&lon=-145.7668&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Alaska Regional Office - Parties: FAA, Bureau d'Enquêtes et d'Analyses - NTSB case key (mKey): 101933 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC20LA089 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/101933/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=101933 - Page: https://openairdocs.org/ntsb/ANC20LA089 ## Probable cause Failure of the door lock due to interference between the door and a cargo box. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Doors: passenger/crew doors](https://openairdocs.org/ntsb-findings/01035210): Aircraft › Aircraft structures · Failure (probable cause); cases with it: [Eurocopter AS 350 B3, 1 case](https://openairdocs.org/ntsb-findings/01035210/cases.md?model=8680954), [All aircraft, 86 cases](https://openairdocs.org/ntsb-findings/01035210/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) (defining event); cases with it: [Eurocopter AS 350 B3, 2 cases](https://openairdocs.org/ntsb-events/338/sequence.md?model=8680954), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) ## Analysis While in cruise flight, at about 700 ft above ground level and 110 kts, a “sudden loud bang” and associated left yaw was experienced as the sliding left side cabin door vacated the helicopter from the closed position. The door impacted a main rotor blade during the separation sequence, which resulted in substantial damage. Subsequently an emergency landing was made to a nearby grass area with no further incident. Airbus Helicopters has two Alert Service Bulletins (ASB) out for the cabin doors on the AS350-B3. The operator reported that the ASBs from the helicopter manufacturer regarding the cabin doors had not been complied with prior to the accident. During a post-accident examination, the FAA inspector reported that he was not able to find any definitive reason for the departure of the door. He added that the door rollers were displaced and were not recovered, and a partial slide piece on the lower rail was not recovered either. Since the door rollers were not recovered, they were not able to be examined, and therefor their condition and function could not be tested. Airbus Helicopters has two Alert Service Bulletins (ASB) published in response to door seperations that occurred as a result of door roller failures on AS350-B3 helicopters. The operator reported that these ASBs had not been complied with prior to the accident. Because the affected components were not recovered, the investigation could not determine if compliance with these ASBs could have prevented the accident. Airbus noted that the damage was consistent with the door lock not being effective due to the presence of a cargo box that was stored in the cabin that interfered with the door, which resulted in the door opening and separating in flight due to the interference load introduced by the cargo box in the cabin. Although some affected components were not recovered and examined, the accident is consistent with the door lock failing inflight, likely due to interference between the door and the cargo box. ## Factual narrative On September 6, 2020, about 0905 Alaska daylight time, a Eurocopter AS350 B3, N354PA, was substantially damaged when it was involved in an accident near Fort Greely, Alaska. The pilot and one crew member were not injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 ferry flight. The pilot reported that while in cruise flight, at about 700 ft above ground level and 110 kts, a “sudden loud bang” and associated left yaw was experienced as the left passenger door vacated the helicopter. The door impacted a main rotor blade during the separation sequence, which resulted in substantial damage. Subsequently, an emergency landing was made to a nearby grass area with no further incident. The pilot added that the door had not been used other than to check it for security for preflight purposes and was checked by both himself and the mechanic by habit before flight. Airbus Helicopters has two Alert Service Bulletins (ASB) in response to sliding cabin door separations on AS350-B3 model helicopters, ASB No. AS350-52.00.53 and ASB No. AS350-52.00.54. Compliance with ASB No. AS350-52.00.53 results in the addition of a label on the sliding cabin door and states in part: Airbus Helicopters was informed that the LH rear support that attaches the rear intermediate roller of the sliding door was found cracked. After investigation, it was confirmed that pushing on the rear part of the rear support was the root cause of the crack appearance. Airbus Helicopters thus makes it mandatory not to push on the rear part of the LH and/or RH rear support covers when closing the door. Compliance with this ALERT SERVICE BULLETIN consists in checking the LH and/or RH rear supports to make sure that there are no cracks, before adding a label that prohibits any pushing in this area. The ALERT SERVICE BULLETIN is to be complied within 6 months from receipt of the ALERT SERVICE BULLETIN that was issued on 06-18-2020. ASB No. AS350-52.00.54 covers the inspection of the upper rail and roller of the left and/or right cabin sliding doors and states in part: The purpose of this ALERT SERVICE BULLETIN is to make sure that the upper rail and roller of the LH and/or RH sliding doors device are in good condition. Compliance is mandatory. The reason for the ALERT SERVICE BULLETIN was the loss of a door that was locked in the open position during flight, the analyses of the degradations found on the fixed parts of the helicopter and on the sliding door indicated that the loss of the sliding door resulted from the disengagement of the roller from the upper rail, which led to the separation of the door. The ALERT SERVICE BULLETIN is stated to need to be complied with by either 165 flight hours or 13 months and 6 days (the first limit reached is applicable). The ALERT SERVICE BULLETIN was issued on 06-18-2020. The last event that led to the release of the SIN 3441-S-52 was in 2019 with a loss of a sliding door. Airbus Helicopters reported they are aware of 11cases of sliding door loss events over the past 28 years and reported the reasons for those loss of doors was for maintenance (incorrect installation/check) or operational (incorrect lock of the door) reasons. The operator reported that the ASBs from the helicopter manufacturer regarding the cabin doors had not been complied with prior to the accident. A Federal Aviation Administration aviation safety inspector examined the helicopter. He noted the door rollers were displaced and were not recovered, and a partial slide piece on the lower rail was not recovered either. He added that the door hinges all looked normal, minus the two areas where the door slides had separated. He also stated that two witnesses confirmed the cabin door was closed prior to the takeoff. A post-accident examination of the door indicated that the latches and locking finger were found undamaged. The rubber seal around the door was perforated at the locking finger level. It was noted there was a cargo box in the cabin that was close to the door, and the cargo box had witness marks (white marks) corresponding to contact with the door. There was no visible damage to the forward upper fitting rail; the lower forward fitting was found deformed; the aft median rail showed deformation; and the lower rail also showed interference. Airbus helicopters noted that the damage was consistent with the door lock not being effective due to the presence of a cargo box that was stored in the cabin that interfered with the door. ## Aircraft - Registration: [N354PA](https://openairdocs.org/aircraft/N354PA), registered now, S/N 3330, built 2000 (OpenAirDocs) - Reported make and model: EUROCOPTER AS 350 (B3) - Registry model: [Eurocopter AS 350 B3](https://openairdocs.org/model/eurocopter-as-350-b3) (registry code 8680954) (OpenAirDocs) - Registry engine: [Turbomeca ARRIUS-2B series](https://openairdocs.org/engine/turbomeca-arrius-2b-series) (registry code 60013, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 3330 - Year built: 2000 - Airframe hours: 15111 - Engines: TURBOMECA ARRIEL 2B 952 horsepower turbo shaft - Damage: Substantial damage - Flight: Positioning, Part 91 - Operator: Pathfinder Aviation - Registered owner: Pathfinder Aviation - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, August 20, 2020 - Departed: 72AK, Delta Junction, AK - Destination: MRI, Anchorage, AK - Flight plan: Company VFR - Equipment: Satellite tracking device, ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 42; injuries: none; commercial; medical: class 2, without waivers/limitations; last flight review February 7, 2020; seat: front; restraint: 4-point; flight hours: 5,437 total, 3,350 in this make and model, 5,276 as pilot in command, 222 in the last 90 days, 114 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 100° at 9 knots - Visibility: 10 statute miles - Temperature: 36 °F, dew point 34 °F - Altimeter: 30.35 inHg - Observed at: PABI, 1 nm away ## 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 20200906012609A](https://openairdocs.org/incident/20200906012609A), Sep 6, 2020: Eurocopter AS 350 B3, Ft. Greely, AK, Substantial damage. Pilot stated that shortly after takeoff and established cruise the door suddenly departed the aircraft with no warning or indication of being partial open. The… ## Docket (8 files) The files NTSB released with the investigation on January 14, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=101933. 2.3 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 178 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11770931&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf - FAA roc (item 2, PDF, 3 pages, 118 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11771398&FileExtension=pdf&FileName=FAA%20Email_Redacted-Rel.pdf - Airbus roc (item 3, PDF, 1 page, 92 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11910852&FileExtension=pdf&FileName=Airbus%20ROC-Rel.pdf - Company emails (item 4, PDF, 2 pages, 64 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11770497&FileExtension=pdf&FileName=Company%20Email_Redacted-Rel.pdf - Safety information notice (item 5, PDF, 3 pages, 272 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11771164&FileExtension=pdf&FileName=3441-S-52-Rev-2-EN-Rel.pdf - Alert service bulletin (53) (item 6, PDF, 11 pages, 540 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11771231&FileExtension=pdf&FileName=ASBAS350520053ENR0-Rel.pdf - Alert service bulletin (54) (item 7, PDF, 10 pages, 393 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11771241&FileExtension=pdf&FileName=ASBAS350520054ENR1-Rel.pdf - Accident pictures (item 8, PDF, 5 pages, 627 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11771154&FileExtension=pdf&FileName=Accident%20Pictures-Rel.pdf 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.