# NTSB SEA06LA162: Kaman HH-43F, N559D, Metaline Falls, WA, August 18, 2006 - Type: NTSB accident investigation - Classification: Accident · Fatal · Limited investigation · Final report - Date: August 18, 2006, 16:00 local (23:00 UTC) - Place: Metaline Falls, WA - Coordinates: 48.82722, -117.296669 - Nearby events: https://openairdocs.org/map.md?lat=48.8272&lon=-117.2967&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Fatal - Injuries: 1 fatal - Status: Completed, report August 30, 2007 - Report: Approved by Office Director - Parties: Kaman Aerospace, Federal Aviation Administration, Honeywell Aerospace - NTSB case key (mKey): 64377 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA06LA162 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/64377/pdf - Page: https://openairdocs.org/ntsb/SEA06LA162 ## Probable cause The failure of the left-hand cross-shaft input internal spline while the helicopter was in a hover, which resulted in the loss of gear box timing, in-flight blade contact and separation, and the subsequent loss of control and impact with a log deck. ## 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, hover - out of ground effect - rotor drive system,engine to transmission drive - failure (cause) - Loss of control - in flight, descent - emergency - In flight collision with terrain/water, descent - uncontrolled - terrain condition - ground ## Analysis The pilot was about to release a load of logs onto a log pile from an altitude between 150 to 200 feet when ground crewmen heard an explosion, then observed the helicopter descend in a nose down attitude before impacting the log deck. An examination of the accident site by an FAA inspector revealed that all major portions of the helicopter were accounted for. A subsequent examination of the wreckage revealed a failure of the transmission's left-hand cross-shaft internal spline, which resulted in the loss of gearbox timing and subsequent in-flight blade contact and separation. Maintenance records revealed that the helicopter's transmission was overhauled on May 1, 2006; the time between the overhaul and the accident was 409.4 hours. An examination of the fractured transmission center housing was caused by two fatigue cracks, which were probably caused by severe cyclic stresses that resulted from repeated loading and unloading of logs. ## Factual narrative HISTORY OF FLIGHT On August 18, 2006, approximately 1600 Pacific daylight time, a Kaman HH-43F helicopter, N559D, was destroyed following a loss of control and impact with a log pile about 5 nautical miles southeast of Metaline Falls, Idaho. The helicopter was registered to a private individual and operated by Horizon Helicopters of Laclede, Idaho. The commercial pilot, sole occupant of the aircraft, sustained fatal injuries. Visual meteorological conditions prevailed for the logging operation, which was conducted in accordance with 14 CFR Part 133, and a flight plan was not filed. The flight departed from the accident/staging site approximately 1530. A ground crewman who witnessed the accident and was working at the accident site reported that the pilot was in the process of dropping logs on a log pile from an altitude of between 150 feet to 200 feet above the ground when he heard an explosion. The ground crewman further reported that he "...observed fragments of blades going everywhere. [I] turned to the helicopter [and] it was coming down nose first before impacting the log deck." A second witness to the accident reported hearing a loud noise and "...observing the top blown off and debris go everywhere before seeing the helicopter drop." On August 19, 2006, the wreckage was recovered from the accident site and transported to the operator's facility in Laclede, Idaho, where a detailed examination would be conducted at a later date. PERSONNEL INFORMATION A review of the Federal Aviation Administration (FAA) Airman and Medical Records databases disclosed that the pilot held a commercial pilot certificate with ratings for rotorcraft-helicopter and instrument helicopter. The pilot also held an instructor rating in helicopters. A second-class medical certificate was issued to the pilot on December 9, 2005, without limitations. On his most recent application for an aviation medical certificate the pilot reported a total time of 2,000 hours, with 500 hours flown in the past 6 months. Company records indicated that the pilot had accumulated the following flight hours in make and model: 897 total flight hours, 400 hours in the previous 90 days, and 7.2 hours in the last 24 hours. AIRCRAFT INFORMATION Horizon Helicopters holds the Type Certificate number "H1NW" for N559D, serial number 62-4514, a Kaman HH-43F series rotorcraft. (Refer to Attachment TC-I). The helicopter was acquired by the United States military and subsequently certificated by the Federal Aviation Administration for restricted category operations. N559D was powered by a Honeywell Aerospace T53-L-13B turboshaft engine, serial number LE-23398B, rated at 1,400 shaft horsepower. The operator reported that the helicopter was maintained in accordance with the FAA's Continuous Airworthiness Inspection Program with its most recent phase inspection having been completed on July 20, 2006, at a total airframe time of 7,960.3, and an engine total time of 4,263.5 hours; the total airframe time at the time of the accident was reported as 8,028.6 hours. Maintenance records further revealed that the engine was overhauled on July 2, 2004, at a total time of 2,910 hours, and that its last hot section inspection occurred on April 18, 2006, at an engine total time of 3,922.6 hours; 1,012.6 hours since being overhauled. Records also revealed that the helicopter's transmission assembly, part number K774502-3, serial number B18-7, was overhauled on May 1, 2006, at a component total time of 3,666.7 hours, a bearing total time of 646.0 hours, and a total airframe time of 7,619.2 hours. At the time of the accident the transmission had accumulated 409.1 hours since overhaul. (Refer to the attached Kaman HH-43 Component Historical Record - Transmission Assembly, and the Main Transmission Overhaul Data sheet.) WRECKAGE AND IMPACT INFORMATION An on scene examination of the wreckage by an FAA airworthiness inspector revealed that the helicopter came to rest on its left side facing in an east-southeast direction in a forested clearing used as its operational base for logging operations. The inspector reported the physical location of the accident site was at coordinates 48 degrees 49.515 minutes north latitude and 117 degrees 17.785 minutes west longitude, at an elevation of 2,602 feet mean sea level. The accident site was approximately 4.3 nautical miles southeast of Metaline Falls, with the main wreckage located about 130 feet west of the west shoreline of Sullivan Lake. The inspector reported that his on scene examination indicated that all major portions of the helicopter had been accounted for. With respect to the wreckage distribution, the inspector revealed that the left-hand transmission tower was found 63 feet west of the main wreckage, while the right hand transmission was located 57 feet southwest of the main wreckage site. The helicopter's exhaust pipe was found 52 feet northwest of the main wreckage, the tail section located 20 feet northeast of the wreckage, while multiple pieces of the helicopter's main rotor blades came to rest in an area from northeast through southeast, approximately 80 to 100 yards from the main wreckage. MEDICAL AND PATHOLOGICAL INFORMATION On August 22, 2006, an autopsy was performed on the pilot by the Deputy Medical Examiner, Office of The Medical Examiner, Spokane, Washington. The cause of death was determined to be "blunt force impact of the head". Toxicology was performed by the FAA Civil Aeromedical Institute, Oklahoma City, Oklahoma. Test for carbon monoxide and cyanide were negative, while 24 (mg/dL, mg/hg) of Ethanol was detected in Urine. It was noted that "the ethanol found in this case is from sources other than ingestion." No drugs were detected in the Blood. TESTS AND RESEARCH On September 6, 2006, at the request of the NTSB IIC, an airworthiness inspector from the FAA Flight Standards District Office, Spokane, Washington, accompanied by the Rotorcraft Program Manager assigned to the Seattle Aircraft Certification Office, Seattle, Washington, provided oversight during an inspection of the helicopter conducted by personnel from Honeywell Aerospace, Phoenix, Arizona, and Kaman Aerospace Corporation, Bloomfield, Connecticut. The examination revealed a failure of the left-hand cross-shaft internal spline, which resulted in the loss of gearbox timing and subsequent in-flight blade contact and separation. The examination further revealed that the left and right transmission heads were separated. The female drive splines connecting the left and right aircraft transmission heads were stripped; the male drive shaft splines were intact. An examination of the aircraft's engine revealed that there was shredded wood debris located in the inlet housing, foreign object damage to the leading edge of the first-stage axial compressor blades, and metal spray deposits of the suction side of the vanes of the second-stage power turbine stator. The N2 rotating group was not free to rotate. (Refer to the attached Honeywell Aerospace report.) The fractured transmission center housing was shipped to the NTSB Materials Laboratory, Washington, D.C., by the IIC for examination. A Senior NTSB Metallurgist reported that a visual examination of the center housing revealed the fracture faces contained faceted features characteristic of a casting. Fracture lines emanated from the relief radius between the off-center post and circumferential wall on the lower right side of the off-center post. The exterior surface at the origin of the fatigue crack showed no evidence of mechanical damage. The fracture lines extended outward to a thumbnail feature consistent with the approximate terminus of a fatigue crack. The housing also exhibited a crack that intersected the relief radius between the circumferential wall and the off-center post on the upper right corner of the post. The exterior face of t ## Aircraft - Registration: [N559D](https://openairdocs.org/deregistered/N559D-2013-05-16), registration cancelled 2013-05-16, S/N 62-4514, built 1962 (OpenAirDocs) - Reported make and model: Kaman HH-43F - Registry model: [Kaman HH-43F](https://openairdocs.org/model/kaman-hh-43f) (registry code 4800708) (OpenAirDocs) - Registry engine: [Lycoming T-53 series](https://openairdocs.org/engine/lycoming-t-53-series) (registry code 41549, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 62-4514 - Airframe hours: 8026.8 - Engines: Lycoming T53-L-13B 1400 horsepower turbo shaft - Damage: Destroyed - Flight: External load, Part 133 - Operator: Horizon Helicopters - Registered owner: Gary N. Jorgenson - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Continuous airworthiness, July 1, 2006, 68.3 hours before - Departed: Metaline Falls, WA - Destination: Metaline Falls, WA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 24; injuries: fatal; commercial, flight instructor; instrument ratings: helicopter; medical: class 2, without waivers/limitations; last flight review January 1, 2006; seat: left; toxicology performed; flight hours: 2,000 total, 897 in this make and model, 400 in the last 90 days, 7 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 84 °F, dew point 37 °F - Altimeter: 30.12 inHg - Observed at: DEW, 60 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 20060818017679A](https://openairdocs.org/incident/20060818017679A), Aug 18, 2006: Kaman HH43F, Sullivan Lake, WA, Substantial damage, 1 fatal. (-23) On 08-18-2006, while engaged in logging operations this helicopter and pilot crashed from an altitude of approximately 150 feet onto the log decking… 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.