# NTSB ERA15LA179: Bell 206B, N43CM, Taylors Island, MD, March 24, 2015 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: March 24, 2015, 17:30 local (21:30 UTC) - Place: Taylors Island, MD - Coordinates: 38.502223, -76.171669 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.5022&lon=-76.1717&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report March 6, 2017 - Report: Approved by Office Director - NTSB office: Eastern Region Aviation - Parties: FAA, Bell Helicopter, Rolls Royce - NTSB case key (mKey): 91004 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA15LA179 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/91004/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=91004 - Page: https://openairdocs.org/ntsb/ERA15LA179 ## Probable cause A partial loss of engine power during cruise flight for reasons that could not be determined because postaccident examination of the airframe and engine did not reveal any anomalies that would have precluded normal operation. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined; cases with it: [Bell 206B, 9 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=1181511), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-cruise: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Bell 206B, 4 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=1181511), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Autorotation: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Bell 206B, 21 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=1181511), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The commercial pilot reported that the helicopter was in cruise flight when he heard a "loud bang," which was followed by a partial loss of engine power. He performed an autorotation to shallow water near a shore, where the tailboom sustained substantial damage. A postaccident examination of the airframe and engine, which included an engine operational check, revealed no evidence of any mechanical malfunctions or failures that would have precluded normal operation. The loss of engine power that occurred during the accident flight could not be duplicated during a test run. Following the engine test run, the fuel control unit (FCU) was removed and tested separately. Tests revealed that the FCU operated erratically due to a bellow anomaly. However, because this condition was discovered only after the engine had successfully completed its test cell runs, a direct correlation could not be drawn between the condition of the FCU and the reported loss of engine power. ## Factual narrative On March 24, 2015, about 1730 eastern daylight time, a Bell 206B, N43CM, was substantially damaged during an autorotation near Taylors Island, Maryland. The commercial pilot and one passenger were not injured. Visual meteorological conditions prevailed and no flight plan was filed. The helicopter was registered to and operated by DC Helicopters Incorporated as a personal flight, which was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. The flight originated from Monmouth Executive Airport (BLM), Farmingdale, New Jersey, about 1530.The pilot reported that the helicopter was in cruise flight at 3,000 feet above ground level, when there was a sudden drop in altitude followed by a 90 degree rotation to the left and a loud "bang." The pilot lowered the collective and noted that the torque gauge went below 10 percent. He then rolled the throttle to idle, entered an autorotation and landed on a shore. Postaccident examination of the helicopter by a Federal Aviation Administration (FAA) inspector revealed that the helicopter's tailboom was buckled near the tail rotor gear box. Further examination revealed that the tail rotor drive shaft was broken. Flight control continuity was confirmed by hand movement of the controls. The cyclic exhibited free movement in all quadrants and the collective exhibited free up and down movement. Corresponding control movement was observed up to the main rotor hub assembly. The tail rotor pedals were moved and control movement was seen at the tail rotor. Drive continuity was established through the drive system with movement observed to the main mast and to the tail rotor drive system. The tail rotor driveshaft on the tailboom exhibited a torsional crack. The tailboom exhibited evidence of tail rotor blade strikes. Both fuel boost pumps were shown to operate when the battery was turned on. The airframe fuel filter was removed and found to be filled with clear and clean fuel and the filter was also clean. The fuel valve was in the off position and motored on when the battery and fuel valve were switched on. The boost pumps were then energized and a steady flow of fuel was present out the "IN" line to the airframe fuel filter. During a postaccident examination of the engine all B-nuts and fittings were checked by hand for torque, and none were loose. The bleed valve was checked by hand for proper operation. The valve operated smoothly with no lateral play of the poppet valve. The engine mounts were intact with no apparent deformities. The engine exhibited no evidence of having been damaged during the accident sequence. The engine cowlings were removed to facilitate examination of the compressor inlet. Examination of the compressor revealed no evidence of compressor damage or failure. Both the N1 (compressor) and N2 (power turbine) rotor systems were rotated by hand. The N1 rotated smoothly with no unusual noise or resistance. Continuity from the compressor through the auxiliary gearbox to thestarter/generator was confirmed. Rotation of the N2 confirmed continuity to both the main rotor and tail rotor drives. The engine was removed to be run in a test cell in an attempt to replicate the reported loss of power. A pre-run examination of the engine found no anomalies with the engine, or any damage which might preclude running the engine on a test cell. The engine was installed on a test cell, started, ran normally and met all serviceable engine standards. The engine produced normal power and responded properly to all power demands, including wave-off and sudden throttle and load changes. After the engine test run, the owner of the helicopter sent the engine's fuel control unit (FCU) out for testing. During testing it was noted that one of the technicians found a "slight bend" in the FCU bellow's assembly. The condition of the bellows did not warrant rejection, and the FCU was reassembled and tested in accordance with manufacturer's specifications. During the test it was noted that the FCU performed erratically on the test stand, and failed to meet serviceable standards. The bellows assembly was replaced with an overhauled bellows assembly, and the FCU performed satisfactorily. The subject bellows assembly was then installed on a serviceable FCU, tested, and failed to pass serviceable standards. ## Aircraft - Registration: [N43CM](https://openairdocs.org/deregistered/N43CM-2018-02-28), registration cancelled 2018-02-28, S/N 2025, built 1976 (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: 2025 - Year built: 1976 - Airframe hours: 6677.5 - Engines: Rolls-Royce 250 C20B 425 horsepower turbo shaft - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, January 4, 2015, 8 hours before - Departed: BLM, BELMAR, NJ - Destination: RIC, RICHMOND, VA - Equipment: Electronic flight bag or handheld device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 45; injuries: none; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, without waivers/limitations; seat: right; restraint: 3-point; flight hours: 1,308 total, 109 in this make and model, 1,308 as pilot in command, 35 in the last 90 days, 6 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 10° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 45 °F, dew point 19 °F - Altimeter: 30.32 inHg - Observed at: CGE, 2 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 20150324004229A](https://openairdocs.org/incident/20150324004229A), Mar 24, 2015: Bell 206B, Taylors Island, MD, Substantial damage. Pilot stated during level cruise there was a sudden drop in altitude, followed by a 90 degree rotation to the left. The pilot performed autorotation into the… ## Docket (6 files) The files NTSB released with the investigation on January 5, 2017, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=91004. 6.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 4.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40447975&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Pilot's Statement (item 2, .PDF, 13 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40447976&FileExtension=.PDF&FileName=Pilot%27s%20Statement-Master.PDF - Airframe Annual Inspection Logbook excerpt (item 3, .PDF, 219 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40447979&FileExtension=.PDF&FileName=Airframe%20Annual%20Inspection%20Logbook%20%20excerpt-Master.PDF - Engine Annual Inspection Logbook excerpt (item 4, .PDF, 170 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40447980&FileExtension=.PDF&FileName=Engine%20Annual%20Inspection%20Logbook%20excerpt-Master.PDF - Fuel control unit test (item 5, .PDF, 66 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40447981&FileExtension=.PDF&FileName=Fuel%20control%20unit%20test-Master.PDF - Accident photos (item 6, .PDF, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40447982&FileExtension=.PDF&FileName=Accident%20photos-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. --- 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.