# NTSB ERA11IA091: Eurocopter Deutschland MBB-BK 117 C-1, N271NE, Boston, MA, December 4, 2010

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: December 4, 2010, 09:00 local (14:00 UTC)
- Place: Boston, MA
- Coordinates: 42.336112, -71.105834 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=42.3361&lon=-71.1058&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Defining event: [Approach: Fire/smoke (non-impact)](https://openairdocs.org/ntsb-events/150)
- Highest injury: No injuries
- Injuries: 4 uninjured
- Status: Completed, report January 17, 2012
- Report: Approved by Office Director
- NTSB office: Eastern Region Aviation
- Parties: FAA/FSDO, FAA/Rotorcraft Directorate
- NTSB case key (mKey): 78008
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA11IA091
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/78008/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=78008
- Page: https://openairdocs.org/ntsb/ERA11IA091

## Probable cause

Improper installation of wiring associated with a medical cabinet interior, which resulted in chafing and a subsequent in-flight fire. Contributing to the incident was inadequate maintenance procedures for continued airworthiness.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Equipment/furnishings: equ/fur sys wiring](https://openairdocs.org/ntsb-findings/01022597): Aircraft › Aircraft systems · Fatigue/wear/corrosion (probable cause); cases with it: [Eurocopter Deutschland MBB-BK 117 C-1, 1 case](https://openairdocs.org/ntsb-findings/01022597/cases.md?model=5626025), [All aircraft, 2 cases](https://openairdocs.org/ntsb-findings/01022597/cases.md)
- [Maintenance: modification/alteration](https://openairdocs.org/ntsb-findings/02062030): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Eurocopter Deutschland MBB-BK 117 C-1, 1 case](https://openairdocs.org/ntsb-findings/02062030/cases.md?model=5626025), [All aircraft, 69 cases](https://openairdocs.org/ntsb-findings/02062030/cases.md)
- [Equipment/furnishings: equ/fur sys wiring](https://openairdocs.org/ntsb-findings/01022597): Aircraft › Aircraft systems · Related maintenance info (probable cause); cases with it: [Eurocopter Deutschland MBB-BK 117 C-1, 1 case](https://openairdocs.org/ntsb-findings/01022597/cases.md?model=5626025), [All aircraft, 2 cases](https://openairdocs.org/ntsb-findings/01022597/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Approach: Fire/smoke (non-impact)](https://openairdocs.org/ntsb-events/150) (defining event); cases with it: [Eurocopter Deutschland MBB-BK 117 C-1, 1 case](https://openairdocs.org/ntsb-events/150/sequence.md?model=5626025), [All aircraft, 504 cases](https://openairdocs.org/ntsb-events/150/sequence.md)

## Analysis

During the air ambulance flight, the helicopter was on final approach to land when smoke and flames were observed emanating from the suction control mounted on the left side of the cabin. The fire was subsequently extinguished, and the pilot landed the helicopter without further incident. Postincident examination revealed fire damage on the face of an overhead medical cabinet that was part of a medical interior installed about 7.5 years prior to the incident per a supplemental type certificate. A sheathed wiring bundle for a 120-volt alternating current power outlet mounted in the aft end of the cabinet displayed chafing damage and arcing consistent with rubbing on the metal housing for the vacuum control switch. The wiring was installed without adequate clearance or support to prevent it from chafing on the switch housing. The helicopter was maintained under an approved inspection program; however, review of the instructions for continued airworthiness associated with the medical cabinet installation did not reveal any required inspections of the associated wiring harnesses for general condition or chafing.

## Factual narrative

On December 4, 2010, about 0900 eastern standard time, a Eurocopter Deutschland GMBH, MBB-BK117-C1, N271NE, sustained minor damage when it experienced an in-flight electrical fire, while on approach to the Brigham & Women's Hospital Heliport (MA39), Boston, Massachusetts. The helicopter was owned by New England Life Flight, doing business as Boston MedFlight, and operated by ERA Med LLC, as an air ambulance flight conducted under the provisions of 14 Code of Federal Regulations Part 135. The airline transport pilot, flight nurse, flight paramedic, and patient were not injured. Visual meteorological conditions prevailed and a company flight plan had been filed for the flight that departed from Oak Bluffs, Massachusetts. According to the flight nurse, the helicopter was on final approach to land, when she noticed "a smell" followed by smoke and flames emanating from the suction control mounted on the left side of the cabin. She notified the pilot and discharged a fire extinguisher, which extinguished the fire. The pilot landed the helicopter without further incident. He subsequently noted obvious fire damage on the left cabin wall near the suction device control switch and the liquid oxygen gauge. Post incident inspection by a Federal Aviation Administration (FAA) inspector revealed fire damage on the face of the overhead medical cabinet around the vacuum control switch. The cabinet was part of a medical interior that was installed per a supplemental type certificate (STC) during May 2003, and housed a vacuum regulator, vacuum pump switch, liquid oxygen quantity indicator and 120-volt alternating current (AC) electrical outlets. A sheathed wiring bundle for the 120-volt AC power outlet mounted in the aft end of the cabinet displayed chafing damage and arching consistent with rubbing on the metal housing for the vacuum control switch. In addition, an approximate 2-inch portion of composite material, which surrounded the switch, was consumed by fire. Additional examination was performed by an FAA inspector, who reported that the wiring was installed without adequate clearance or support to prevent it from chafing on the switch housing. The electrical power to the outlets was supplied by a KGS Electronics SPS-1607A medical inverter system, which was installed per an STC during June 2003. Review of the instructions for continued airworthiness associated with the medical cabinet installation did not reveal any required inspections of the associated wiring harnesses for general condition or chafing. The helicopter was maintained under an FAA approved inspection program and had been operated for approximately 254 hours since its most recent 300 hour/12 month inspection, which was performed on August 12, 2010. Item 24 on the inspection checklist included: "Visually inspect inverter and mounting for damage, security and electrical connections" and "Test medical inverter for proper operation," with a reference to the KGS-SPS-1607A Removal/InstallationManual. Review of the KGS-SPS-1607A Removal/Installation Manual revealed instructions for removal and installation. Under instructions for maintenance, the manual stated "No regular periodic maintenance is required for this product. Service is required only when a malfunction is detected. Maintenance consists of removal and replacement." An FAA check of service difficulty reports for the BK117 did not reveal any previous instances of fires associated with the medical cabinet installation. FAA Advisory Circular AC65-15A, Airframe and Powerplant Mechanics Airframe Handbook, Chapter 11, Aircraft Electrical Systems, Protection Against Chafing, stated in part: "Wires and wire groups should be protected against chafing or abrasion in those locations where contact with sharp surfaces or other wires would damage the insulation. Damage to the insulation can cause short circuits, malfunction, or inadvertent operation of equipment…."

## Aircraft

- Registration: [N271NE](https://openairdocs.org/deregistered/N271NE-2019-12-11), registration cancelled 2019-12-11, S/N 7543, built 2002 (OpenAirDocs)
- Reported make and model: EUROCOPTER DEUTSCHLAND GMBH MBB-BK 117 C-1
- Registry model: [Eurocopter Deutschland MBB-BK 117 C-1](https://openairdocs.org/model/eurocopter-deutschland-mbb-bk-117-c-1) (registry code 5626025) (OpenAirDocs)
- Registry engine: [Turbomeca ARRIEL-1](https://openairdocs.org/engine/turbomeca-arriel-1) (registry code 60043, turbo-shaft) (OpenAirDocs)
- Category: Helicopter
- Serial number: 7543
- Airframe hours: 4959
- Engines: Turbomeca Ariel 1E2 738 horsepower turbo shaft; Turbomeca Ariel 1E2 738 horsepower turbo shaft
- Damage: Minor damage
- Fire: In-Flight
- Flight: Part 135
- Operator: ERA Med LLC, doing business as Boston MedFlight
- Registered owner: New England Life Flight Inc
- Airworthiness certificate: Standard, Utility
- Last inspection: AAIP, December 1, 2010, 254 hours before
- Departed: Oak Bluffs, MA
- Destination: MA39, Boston, MA
- Flight plan: Company VFR
- Airport: MA39, Brigham & Women's Hospital

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 35; injuries: none; airline transport, flight instructor; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 1, without waivers/limitations; last flight review October 12, 2010; seat: right; flight hours: 4,465 total, 533 in this make and model, 4,121 as pilot in command, 47 in the last 90 days, 15 in the last 30 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 300° at 17 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 36 °F, dew point 19 °F
- Altimeter: 29.65 inHg
- Observed at: BOS, 5 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 20101204052739I](https://openairdocs.org/incident/20101204052739I), Dec 4, 2010: Eurocopter MBB-BK 117, Bostn, MA, Minor damage. *During landing it was observed by the medical crew that the face of the overhead medical cabinet assy was on fire around the vacuum control switch (VAC1).…

## Docket (13 files)

The files NTSB released with the investigation on December 2, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=78008. 3.4 MB in all.

- Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 and Crew Statements (item 1, .PDF, 620 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358564&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1%20and%20Crew%20Statements-Redacted.PDF
- FAA FSDO Inspector Statement (item 2, .PDF, 33 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358574&FileExtension=.PDF&FileName=FAA%20FSDO%20Inspector%20Statement-Master.PDF
- Company Service Difficulty Report (SDR) (item 3, .PDF, 84 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358567&FileExtension=.PDF&FileName=Company%20Service%20Difficulty%20Report%20(SDR)-Master.PDF
- Supplemental Type Certificate and FAA Maintenance Records (excerpts) (item 4, .PDF, 997 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358547&FileExtension=.PDF&FileName=Supplemental%20Type%20Certificate%20and%20FAA%20Maintenance%20Records%20(excerpts)%20-Redacted.PDF
- ERA 300 Hour/12 Month Inspection Checklist (item 5, .PDF, 388 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358550&FileExtension=.PDF&FileName=ERA%20300%20Hour%2F12%20Month%20Inspection%20Checklist-Master.PDF
- FAA AC 43.13-1B – Chapter 11 Aircraft Electrical Systems (excerpts) (item 6, .PDF, 423 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358553&FileExtension=.PDF&FileName=FAA%20AC%2043.13-1B%20%E2%80%93%20Chapter%2011%20Aircraft%20Electrical%20Systems%20(excerpts)-Master.PDF
- FAA AC 65-15A – Airframe and Powerplant Mechanics Handbook (excerpts) (item 7, .PDF, 97 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358555&FileExtension=.PDF&FileName=FAA%20AC%2065-15A%20%E2%80%93%20Airframe%20and%20Powerplant%20Mechanics%20Handbook%20(excerpts)-Master.PDF
- Helicopter Accident/Incident Checklist Supplement (item 8, .PDF, 113 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358570&FileExtension=.PDF&FileName=Helicopter%20Accident%2FIncident%20Checklist%20Supplement-Master.PDF
- Photograph # 1 – View of fire damage on installed medical cabinet (Courtesy of the Operator) (item 9, .PDF, 188 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358575&FileExtension=.PDF&FileName=Photograph%20%23%201%20%E2%80%93%20View%20of%20fire%20damage%20on%20installed%20medical%20cabinet%20(Courtesy%20of%20the%20Operator)-Master.PDF
- Photograph # 2 – View of front on side of medical cabinet assembly after removal. (Courtesy of the FAA) (item 10, .PDF, 341 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358578&FileExtension=.PDF&FileName=Photograph%20%23%202%20%E2%80%93%20View%20of%20front%20on%20side%20of%20medical%20cabinet%20assembly%20after%20removal.%20(Courtesy%20of%20the%20FAA)-Master.PDF
- Photograph # 3 – View of wires installed within the medical cabinet (Courtesy of the FAA) (item 11, .PDF, 32 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358579&FileExtension=.PDF&FileName=Photograph%20%23%203%20%E2%80%93%20View%20of%20wires%20installed%20within%20the%20medical%20cabinet%20%20(Courtesy%20of%20the%20FAA)-Master.PDF
- Photograph # 4 – View of chafed wire (Courtesy of the FAA) (item 12, .PDF, 49 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358580&FileExtension=.PDF&FileName=Photograph%20%23%204%20%E2%80%93%20View%20of%20chafed%20wire%20%20(Courtesy%20of%20the%20FAA)-Master.PDF
- Photograph # 5 – View of aircraft sidewall after medical cabinet was removed. (Courtesy of the FAA) (item 13, .PDF, 36 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358582&FileExtension=.PDF&FileName=Photograph%20%23%205%20%E2%80%93%20View%20of%20aircraft%20sidewall%20after%20medical%20cabinet%20was%20removed.%20(Courtesy%20of%20the%20FAA)-Master.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.

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