# NTSB SEA07LA108: Hughes 369D, N911FT, Kahuku, HI, April 20, 2007 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: April 19, 2007, 14:05 local (Apr 20, 2007, 00:05 UTC) - Place: Kahuku, HI - Coordinates: 21.704721, -158.005554 - Nearby events: https://openairdocs.org/map.md?lat=21.7047&lon=-158.0056&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 2 minor, 2 uninjured - Status: Completed, report April 30, 2008 - Report: Approved by Office Director - Parties: Rolls-Royce, FAA FSDO - NTSB case key (mKey): 65605 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA07LA108 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/65605/pdf - Page: https://openairdocs.org/ntsb/SEA07LA108 ## Probable cause Fatigue cracking of the oil line from the engine gearbox to the oil pressure gauge, which resulted in loss of engine lubricating oil, leading to seizure of the power turbine. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(total) - mech failure/malf, approach - vfr pattern - final approach - lubricating system,oil line - fatigue (cause) - lubricating system,oil line - cracked (cause) - fluid,oil - leak (cause) - turboshaft engine,free(power) turbine - seized (cause) - Forced landing, emergency descent/landing - autorotation - performed, pilot in command - Hard landing, emergency descent/landing ## Analysis During an aerial surveillance flight, the helicopter's engine chip light illuminated, and the pilot headed towards a nearby heliport to make a precautionary landing. The pilot established a steep fast approach in case of engine failure while on approach. At approximately 100 feet above the ground and an airspeed of 65 knots, he applied power and began to slow the helicopter. At this point, the engine lost power, and the pilot entered an autorotation. The helicopter landed hard breaking both forward landing gear struts and spreading the rear struts. The main rotor blades impacted the tail boom, and the tail boom separated from the fuselage. Examination of the helicopter revealed heavy deposits of oil on the inner surfaces of the engine compartment as well as on the exterior surfaces of the engine. There was no oil in the airframe engine oil reservoir. The oil line leading from the engine gearbox to the oil pressure gauge was found cracked beneath the "B" nut securing it to the fitting on the engine gearbox. The N2 (power turbine) drive could not be rotated. Partial disassembly of the engine revealed damage to the number six, seven, and eight bearings consistent with a lack of adequate lubrication. Laboratory examination of the cracked oil line found fatigue cracking had propagated through an estimated 90 percent of the cross-sectional area of the tube. The cracking allowed lubricating oil to leak from the line resulting in oil starvation to the bearings leading to seizure of the power turbine. ## Factual narrative On April 19, 2007, approximately 1405 Hawaii standard time, a Hughes 369D helicopter, N911FT, landed hard during an autorotation following a loss of engine power on final approach to Turtle Bay Heliport, Kahuku, Hawaii. The helicopter, which was registered to and operated by K&S Helicopters of Kailua Kona, Hawaii, sustained substantial damage. The commercial pilot and one passenger were not injured, and two passengers received minor injuries. Visual meteorological conditions prevailed and no flight plan was filed for the 14 Code of Federal Regulations Part 135 on demand air taxi flight conducted for the Honolulu Police Department. The purpose of the flight was aerial surveillance. The flight departed from Honolulu International Airport about 1305. According to the pilot, the flight proceeded from Honolulu to the North Shore area without incident. While in the vicinity of the town of Kahuku, the "engine chips" light illuminated, and he headed towards the Turtle Bay Heliport to make a precautionary landing. The pilot established a steep fast approach in case of engine failure while on approach. At approximately 100 feet above the ground and an airspeed of 65 knots, he applied power and began to slow the helicopter. At this point, the engine lost power, and the pilot entered an autorotation. The helicopter landed hard breaking both forward landing gear struts and spreading the rear struts. The main rotor blades impacted the tail boom, and the tail boom separated from the fuselage. Examination of the helicopter by a representative of the engine manufacturer, conducted under the supervision of a Federal Aviation Administration (FAA) inspector, revealed heavy deposits of oil on the inner surfaces of the engine compartment as well as on the exterior surfaces of the engine. There was no oil in the airframe engine oil reservoir. The oil line leading from the engine gearbox to the oil pressure gauge was found cracked beneath the "B" nut securing it to the fitting on the engine gearbox. The N2 (power turbine) drive could not be rotated. Partial disassembly of the engine revealed damage to the number six, seven, and eight bearings consistent with a lack of adequate lubrication. Laboratory examination of the cracked oil line by the NTSB Materials Laboratory found fatigue cracking had propagated through an estimated 90 percent of the cross-sectional area of the tube. Under the supervision of an FAA inspector, the oil pressure gauge was bench tested through its full indicating range and no discrepancies were noted. ## Aircraft - Registration: [N911FT](https://openairdocs.org/deregistered/N911FT-2013-07-15), registration cancelled 2013-07-15, S/N 811036D (OpenAirDocs) - Reported make and model: HUGHES 369D - Registry model: [Hughes Helicopters HUGHES 369D](https://openairdocs.org/model/hughes-helicopters-hughes-369d) (registry code 4470706) (OpenAirDocs) - Registry engine: [Allison 250-C20 series](https://openairdocs.org/engine/allison-250-c20-series) (registry code 03020, turbo-prop) (OpenAirDocs) - Category: Helicopter - Serial number: 811036D - Airframe hours: 14899 - Engines: Rolls-Royce 250-C20B 420 horsepower turbo shaft - Damage: Substantial damage - Flight: Part 135 - Registered owner: K&S Helicopters, Inc. - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, March 1, 2007 - Departed: HNL, Honolulu, HI - Destination: HI58, Kahuku, HI - Airport: HI58, Turtle Bay Hilton Heliport ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 51; injuries: none; commercial, flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane, helicopter; medical: class 2, with waivers/limitations; last flight review December 1, 2006; seat: left; flight hours: 14,000 total, 9,990 in this make and model, 13,804 as pilot in command, 95 in the last 90 days, 19 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 40° at 20 knots - Visibility: 10 statute miles - Lowest ceiling: 10,000 ft broken - Temperature: 72 °F - Altimeter: 30.04 inHg ## 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 20070419008229A](https://openairdocs.org/incident/20070419008229A), Apr 19, 2007: Hughes 369D, Kahuku, HI, Substantial damage. (-23) Including the reporting inspector, four(4) hnl-asi, 2 opps, & 2 a/w, were assigned to this on site investigation, approximately 20 man hours were… ## Other investigations on N911FT (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 LAX92T#A03](https://openairdocs.org/ntsb/LAX92T%23A03), Feb 14, 1992: Mcdonnell Douglas 369D (N911FT), Mesa, AZ, substantial damage 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.