# NTSB CEN10IA372: Eurocopter AS365N3, N520CF, Dayton, OH, July 4, 2010 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: July 4, 2010, 03:09 local (07:09 UTC) - Place: Dayton, OH - Coordinates: 39.682498, -84.242774 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.6825&lon=-84.2428&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: 3 uninjured - Status: Completed, report April 7, 2011 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Federal Aviation Administration, Bureau d’Enquêtes et d’Analyses, American Eurocopter - NTSB case key (mKey): 76540 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN10IA372 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/76540/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=76540 - Page: https://openairdocs.org/ntsb/CEN10IA372 ## Probable cause The unintentional movement of the jettison handle in-flight due to the pilot’s dropping of a manual that impacted the handle and released the door window, which then impacted the horizontal stabilizer. Contributing to the accident was the jettison handle guard not being installed by maintenance personnel. ## 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 · Unintentional use/operation (probable cause); cases with it: [Eurocopter AS365N3, 1 case](https://openairdocs.org/ntsb-findings/01035210/cases.md?model=8680903), [All aircraft, 86 cases](https://openairdocs.org/ntsb-findings/01035210/cases.md) - [Action: incomplete action](https://openairdocs.org/ntsb-findings/02041040): Personnel issues › Action/decision · Maintenance personnel (probable cause); cases with it: [Eurocopter AS365N3, 1 case](https://openairdocs.org/ntsb-findings/02041040/cases.md?model=8680903), [All aircraft, 105 cases](https://openairdocs.org/ntsb-findings/02041040/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 AS365N3, 1 case](https://openairdocs.org/ntsb-events/338/sequence.md?model=8680903), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) ## Analysis The emergency medical services transport helicopter sustained minor damage when a door window separated in-flight. The pilot dropped a flight manual during cruise flight that impacted the right center door jettison handle, allowing the window to separate and impact the horizontal stabilizer. The required jettison handle guard was not installed. The helicopter’s maintenance manual directs that the crew and passenger doors be checked every 600 hours of flight time or every two years. The manual requires the following steps to reinstall the doors, "Install the Plexiglas protective cover." Subsequent to the accident, the helicopter manufacturer issued Safety Information Notices which described the incident and reminded mechanics that while performing routine maintenance procedures, in particular assembly procedures, “it is important to strictly comply with all applicable maintenance procedures, including the most basic and simple ones, to ensure proper helicopter performance and flight safety.” ## Factual narrative On July 4, 2010, about 0309 eastern daylight time, N520CF, a Eurocopter AS365N3 helicopter, operated by Air Methods Corp., sustained minor damage when one of its door windows separated from the helicopter in-flight near Dayton, Ohio. The emergency medical services (EMS) transport flight was conducted under 14 Code of Federal Regulations Part 135, and was en route from the Lebanon-Warren County Airport (I68), near Lebanon, Ohio, to an automobile accident site near Huber Heights, Ohio, when the incident occurred. Visual meteorological conditions prevailed in the area. All three occupants, including the pilot and two crewmembers were uninjured. The flight originated from I68 about 0304. The pilot, according to an operator’s incident report, in part, stated: At 0304 departed I68 for a scene flight in Huber Heights. Around 0309 local heard a loud bang. Asked flight nurse what happened and if she was ok. Flight nurse stated we lost the window and she was ok. At 0310 local, I called the communication center and said we were aborting and landing at Moraine. ... At 0313 local, I called safe on deck at Moraine. The pilot dropped a flight manual during cruise flight. The flight manual impacted the right front passenger door jettison handle, which was safety wired. However, the handle's required protective guard was not installed. The jettison handle rotated rearward, broke its safety wire, and disengaged its center door’s upper pin. The center door’s middle and lower pins did not disengage. The window bent outward and separated from its frame. The separated window subsequently impacted the horizontal stabilizer. According to the helicopter’s trainees hand manual, the helicopter is equipped with a door jettisoning system. The system’s description, in part, included: JETTISONING SYSTEM A handle, locked with snapwire [and] protected by a breakable cover, makes it possible, should it be necessary, to jettison the doors. Actuating the mechanism releases either the studs or the hinge pins. The helicopter’s maintenance manual directs that the crew and passenger doors be removed and checked every 600 hours of flight time or every two years. The manual, in part, lists the following steps to reinstall the doors. FINAL STEPS - Install the pneumatic strut and check for correct engagement of the ball-joints. - Make sure that handle is against stop, then safety jettison lever with snap wire. - Install the plexiglass protective cover. - Safety and lock the door and check: - the locking system is correctly engaged, - the indicating system operation. A Heli-Dyne Systems Inc. supplemental type certificate, SH921NE, was the basis on which the helicopter was modified to install a medical interior. Airworthiness documents showed that this major alteration was field approved by the Federal Aviation Administration(FAA) on January 21, 2005. The helicopter's airworthiness was maintained under a FAA Approved Aircraft Inspection Program (AAIP). The helicopter's most recent AAIPinspection, to include the area of the jettison handle, was completed on June 23, 2010. The helicopter’s illustrated parts catalog identified the Plexiglas jettison handle guard as COVER, JETTISON RH with part number 365A87-3019-87. In a letter to the FAA, the operator, in part, stated: Confusion sets in when [the maintenance manual] uses reference drawings with no "Plexiglas Protective Cover" present. It was believed by the questioned mechanics that the 14 [degree] frame decorative plastic trim was the guard; the decorative plastic trim installed on N520CF could have been removed and installed in the same sequence in place of the “Plexiglas Protective Covers” called out in [the maintenance manual] Subsequent to the accident, the helicopter manufacturer issued Safety Information Notice 2257-S-52 and 2247-S-00. Notice 2257-S-52 described the incident and, in part, stated: Considering that the in-flight loss of an aircraft component can seriously affect the safety of the flight and/or of the persons on the ground, EUROCOPTER reminds you that the content of the technical documentation issued by EUROCOPTER must be strictly complied with, especially regarding the installation of aircraft components during removal/installation or maintenance operations. Any failure to comply with any rules specified in the EUROCOPTER technical documentation may adversely affect the aircraft continued airworthiness and flight safety. We also recommend you to read the Safety Information Notice 2247-S-00, which covers specifically serious accidents/incidents caused by failures in the basic application of maintenance instructions. Notice 2247-S-00 indicated that it was a reminder to mechanics that while performing ‘routine’ applicable maintenance procedures, in particular assembly procedures, “it is important to strictly comply with all applicable maintenance procedures, including the most basic and simple ones, to ensure proper helicopter performance and flight safety.” ## Aircraft - Registration: [N520CF](https://openairdocs.org/deregistered/N520CF-2024-07-27), registration cancelled 2024-07-27, S/N 6537, built 1998 (OpenAirDocs) - Reported make and model: EUROCOPTER AS365N3 - Registry model: [Eurocopter AS365N3](https://openairdocs.org/model/eurocopter-as365n3) (registry code 8680903) (OpenAirDocs) - Registry engine: [Turbomeca ARRIEL-2C](https://openairdocs.org/engine/turbomeca-arriel-2c) (registry code 60054, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 6537 - Airframe hours: 2570 - Engines: TURBOMECA ARRIEL 2C 779 horsepower turbo shaft; TURBOMECA ARRIEL 2C 779 horsepower turbo shaft - Damage: Minor damage - Flight: Part 135 - Operator: Air Methods Corp - Registered owner: Miami Valley Hospital - Airworthiness certificate: Standard, Transport - Last inspection: AAIP, June 23, 2010, 12 hours before - Departed: I68, Lebanon, OH - Destination: Huber Heights, OH - Flight plan: Unknown - Airport: I73, Moraine Air Park ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 45; injuries: none; commercial; instrument ratings: helicopter; medical: class 2, with waivers/limitations; last flight review June 15, 2010; seat: right; flight hours: 4,120 total ## Weather - Conditions: Visual (VMC), Night - Wind: 170° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 70 °F, dew point 63 °F - Altimeter: 30.06 inHg - Observed at: MGY, 6 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). - [Incident 20100704038179I](https://openairdocs.org/incident/20100704038179I), Jul 4, 2010: Eurocopter AS365N3, Dayton, OH, Minor damage. During cruise flight at 2000 feet, the upper front corner of the emergency egress door was dislodged, the airstream caught door and bent the top half down to… ## Other investigations on N520CF (1) 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. - [NTSB ERA22LA334](https://openairdocs.org/ntsb/ERA22LA334), Jul 26, 2022: Eurocopter AS365 (N520CF), Hamilton, OH, substantial damage. Probable cause: The pilot’s decision to continue the landing without having visually identified wires that were known to be in the vicinity of the landing zone, which resulted in a collision with the wires while… ## Docket (5 files) The files NTSB released with the investigation on January 3, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=76540. 3.2 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40341319&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Correspondence - EXCERPT from Air Methods Response to N520CF Emergency Handle Covers (item 2, .PDF, 836 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40341027&FileExtension=.PDF&FileName=Correspondence%20-%20EXCERPT%20from%20Air%20Methods%20Response%20to%20N520CF%20Emergency%20Handle%20Covers-Master.PDF - Other Pertinent Forms and Reports - Maintenance Manual Excerpt (item 3, .PDF, 98 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40341032&FileExtension=.PDF&FileName=Other%20Pertinent%20Forms%20and%20Reports%20-%20Maintenance%20Manual%20Excerpt-Master.PDF - Other Pertinent Forms and Reports - Trainees Hand Manual Excerpt (item 4, .PDF, 335 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40341034&FileExtension=.PDF&FileName=Other%20Pertinent%20Forms%20and%20Reports%20-%20Trainees%20Hand%20Manual%20Excerpt-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 5, .PDF, 676 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40341580&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.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.