# NTSB SEA02IA096: Kaman K-600 (HH-43B), N286M, Cocolalla, ID, May 21, 2002 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: May 20, 2002, 17:45 local (May 21, 2002, 00:45 UTC) - Place: Cocolalla, ID - Coordinates: 48.078609, -116.630279 - Nearby events: https://openairdocs.org/map.md?lat=48.0786&lon=-116.6303&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report May 30, 2003 - Report: Approved by Office Director - Parties: FAA Spokane FSDO - NTSB case key (mKey): 54865 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA02IA096 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/54865/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=54865 - Page: https://openairdocs.org/ntsb/SEA02IA096 ## Probable cause The reverse installation of the RPM compensator assembly control box bolts resulting in the threaded end of the bolt impinging on a clevis and jamming the collective during climb. A contributing factor was the lack of adequate documentation provided by the technical order instruction for installation of the compensator. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, climb - information insufficient, manufacturer (contributing factor) - maintenance,installation - improper (contributing factor) - miscellaneous,bolt/nut/fastener/clamp/spring - reversed (cause) - rotorcraft flight control,collective control - jammed ## Analysis The pilot of the Kaman K-600 (HH-43) rotorcraft began to reduce collective to stop the climb and bring the hook into position for another log pickup when the collective effectively jammed at a high power setting forcing the rotorcraft into a climb. The pilot was able to utilize an alternative means of reducing power and, after flight testing the rotorcraft successfully, landed without damage or injury. Post-incident examination revealed that the four hex head bolts that secure the RPM compensator assembly control box into the cabin ceiling had been installed in reverse; such that each bolt head was at the top of the control box with each threaded bolt end extruding downward through the control box bolt retaining ears. This allowed the clevis of the compensator telescopic unit, linked to the collective, to jam against the extended bolt end. The maintenance instructions contained in the Technical Order (T.O.) for the HH-43 were found to contain no instructions relating to the proper orientation of the bolts at installation. ## Factual narrative HISTORY OF FLIGHT On May 20, 2002, approximately 1745 Pacific daylight time, a Kaman K-600 (HH-43), N286M, registered to/operated by JC Helicopter Services LLC, and being flown by a commercial pilot, sustained a jammed collective condition while entering a hover at a logging site near Cocolalla, Idaho. The pilot was uninjured and the aircraft sustained no damage during the pilot's use of alternate controls to affect an emergency landing. Visual meteorological conditions prevailed and no flight plan had been filed. The flight, which was engaged in logging operations, was operated under 14 CFR 133, and originated from a local site nearby. The pilot reported that he had been engaged in log-slinging operations and that after about two hours while flaring in anticipation of another load pickup, he began to reduce collective to stop the climb and bring the hook into position. He determined that the collective was jammed at a high power setting and could not be reduced further. He was able to stop the climb and establish level flight by applying throttle outside the governed range and selecting manual on the governor control switch. He was then able to initiate a slow descent by reducing RPM and after approximately 20 minutes of practiced flight operations in this regime during which he determined that control response was marginal, he initiated a landing to an open field. Approximately eight feet above ground entering ground effect he began to lose control of the rotorcraft, rolled the throttle to flight idle and executed a successful landing. Post-incident investigation revealed that the four hex head bolts that secure the RPM compensator assembly control box into the cabin ceiling had been installed such that each bolt head was at the top of the control box with each threaded bolt end extruding downward through the control box bolt retaining ears. The threaded (nut) ends of all four bolts were observed extending out the bottom of the control box retaining holes such that the threaded end of each bolt faced down and at least one bolt end was found to interfere with the movement of the RPM compensator telescopic unit clevis (refer to photo 1). Further examination revealed that when the bolts were installed with each hex head end at the bottom of the control box and the nuts at the top, the maximum extension of the bolt from the bottom of the control box was confined to the thickness of the hex head. This installation would ensure that none of the four bolts would interfere with the RPM compensator telescopic unit. AIRCRAFT INFORMATION Timber Choppers, Inc. holds the Type Certificate for the civil variant of the Kaman HH-43 series rotorcraft (refer to Attachment TC-I). N286M, a Kaman K-600, also previously designated for military use as the HH-43B rotorcraft, had been acquired from military surplus and had been certificated by the Federal Aviation Administration for restricted category operations. The total airframe and engine time was not reported and the rotorcraft was reported as being on a continuous airworthiness inspection program with the most recent (phase) inspection being conducted May 20, 2002, four hours prior to the accident. The maintenance instructions contained in the Technical Order (T.O.) for the HH-43 (refer to Attachment TO-I) were reviewed, specifically, the sections covering the removal and installation of the RPM compensator assembly control box. The installation procedure was described under Section III, paragraph 3-91 (x) as follows: "Position control box assembly (13) on cabin ceiling and secure with four bolts, eight washers and four nuts." The Technical Order provided no guidance as to the proper orientation (up or down) for the bolts upon installation. ## Aircraft - Registration: [N286M](https://openairdocs.org/aircraft/N286M), registered now, S/N 110 (OpenAirDocs) - Reported make and model: Kaman K-600 (HH-43B) - Registry model: [Kaman K-600](https://openairdocs.org/model/kaman-k-600) (registry code 4800802) (OpenAirDocs) - Category: Helicopter - Serial number: 110 - Engines: Lycoming T53-L-11 1300 horsepower turbo shaft - Damage: No damage - Flight: Other work use, Part 133 - Registered owner: JC Helicopter Services, LLC - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Continuous airworthiness, May 20, 2002, 4 hours before - Departed: Cocolalla, ID ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 52; injuries: none; flight instructor, commercial; airplane ratings: single-engine land, multi-engine land; medical: class 2, valid medical--w/ waivers/lim; last flight review July 22, 2002; seat: left; flight hours: 16,000 total, 1,000 in this make and model, 15,000 as pilot in command, 300 in the last 90 days, 100 in the last 30 days, 8 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 240° at 11 knots - Visibility: 10 statute miles - Lowest ceiling: 4,400 ft broken - Temperature: 54 °F, dew point 43 °F - Altimeter: 29.79 inHg - Observed at: COE, 20 nm away ## Other investigations on N286M (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 SEA04LA019](https://openairdocs.org/ntsb/SEA04LA019), Nov 20, 2003: Kaman K-600 (N286M), Nordman, ID, substantial damage, 1 fatal. Probable cause: The total failure of the helicopter's right main rotor shaft while in an ascending hover due to the propagation of a fatigue crack that initiated in a corrosion pit on the surface of a slot in the… ## Docket (4 files) The files NTSB released with the investigation on April 14, 2003, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=54865. 5.0 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 328 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40438927&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Attachment TC-I (item 2, .PDF, 271 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40180555&FileExtension=.PDF&FileName=Attachment%20TC-I-Master.PDF - Attachment TO-I (item 3, .PDF, 4.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40180556&FileExtension=.PDF&FileName=Attachment%20TO-I-Master.PDF - Photo 1. A view looking at the underside (bottom) of the RPM compensator assembly control box. Digital Image (item 4, .PDF, 362 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40180557&FileExtension=.PDF&FileName=Photo%201.%20%20A%20view%20looking%20at%20the%20underside%20(bottom)%20of%20the%20RPM%20compensator%20assembly%20control%20box.%20%20Digital%20Image-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.