# NTSB ATL94LA035: Kaman HH-43B/F, N5197W, Mobile, AL, December 29, 1993 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: December 29, 1993, 16:55 local (22:55 UTC) - Place: Mobile, AL - Coordinates: 31.089216, -88.010887 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=31.0892&lon=-88.0109&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report December 2, 1994 - Report: Approved by Office Director - NTSB case key (mKey): 3337 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL94LA035 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/3337/pdf - Page: https://openairdocs.org/ntsb/ATL94LA035 ## Probable cause AN INADEQUATE MAJOR REPAIR BY COMPANY MAINTENANCE PERSONNEL WHO FAILED TO INSTALL THE COTTER PIN WHICH SECURED THE RETAINING NUT OF THE RIGHT MAIN ROTOR HUB TEETER PIN. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, maneuvering - rotor system,main rotor hub retaining nut - loose (cause) - maintenance,major repair - inadequate, company maintenance personnel (cause) - In flight collision with terrain/water, descent - emergency ## Analysis THE HELICOPTER WAS BEING USED FOR EXTERNAL LIFT, LONG-LINE LOGGING OPERATIONS. AFTER LIFTING A LOAD OF LOGS, THE PILOT EXPERIENCED CONTROL PROBLEMS WITH THE HELICOPTER. THE LOAD, AND THEN THE LONG LINE, WERE JETTISONED, AND AN EMERGENCY DESCENT WAS BEGUN TO THE REMOTE, TEMPORARY LOG HELIPORT. AS THE PILOT ATTEMPTED TO SLOW THE HELICOPTER'S DESCENT RATE, CONTROL WAS LOST. POWER WAS REDUCED, A LEVEL ATTITUDE REGAINED, AND THE MAIN ROTOR BLADES CONTACTED THE GROUND. THE FUSELAGE THEN LANDED HARD. THE WRECKAGE WAS EXAMINED, WHICH REVEALED THAT THE COTTER PIN FOR THE RIGHT ROTOR HEAD TEETER PIN RETAINING NUT WAS ABSENT. ABSENCE OF THE COTTER PIN WOULD ALLOW THE TEETER PIN RETENTION NUT TO LOSE TORQUE, AND EVENTUAL SEPARATION OF THE ROTOR HEAD FROM THE HELICOPTER. ## Factual narrative On December 29, 1993, at about 1655 central standard time, a Kaman HH-43B/F, N5197W, collided with the ground during an emergency descent near Mount Vernon, Alabama. The helicopter was operated by Scott Paper Company under 14 CFR Part 133, and visual flight rules. Visual meteorological conditions prevailed. A flight plan was not filed for the external lift, long-line, logging flight. The commercial pilot was not injured, and the helicopter was substantially damaged. The local flight had departed a logging work area at an unspecified time. The pilot reported a partial loss of rotor system control, after lifting an external load of logs. The external load was jettisoned. Control of the helicopter could be maintained while in straight and level flight, with the collective at its lowest pitch setting. As the pilot attempted to slow the helicopter's descent rate for a landing, control was lost. The collective was lowered, and the helicopter collided with the ground. The rotor system contacted the ground and shattered, and the fuselage landed hard. The operator examined the wreckage and discovered that the cotter pin for the right rotor head teeter pin retention nut was absent. Both rotor hub assemblies had been replaced because of normal maintenance action on December 13, 1993. The operator stated that a maintenance action checklist would be developed to supplement the Maintenance Manual to preclude a similar oversight in the future. ## Aircraft - Registration: [N5197W](https://openairdocs.org/deregistered/N5197W-2018-02-08), registration cancelled 2018-02-08, S/N 59-1564, built 1958 (OpenAirDocs) - Reported make and model: KAMAN HH-43B/F - Registry model: [Kaman HH-43 B/F](https://openairdocs.org/model/kaman-hh-43-b-f) (registry code 4800705) (OpenAirDocs) - Registry engine: [Lycoming T-53 series](https://openairdocs.org/engine/lycoming-t-53-series) (registry code 41549, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 59-1564 - Airframe hours: 6068 - Engines: LYCOMING T53-L-13B 1250 horsepower turbo shaft - Damage: Substantial damage - Flight: Other work use, Part 133 - Registered owner: Scott Paper Co. - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, October 14, 1993, 51 hours before - Departed: NONE, MT. VERNON, AL ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 49; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 8,700 total, 700 in this make and model, 8,300 as pilot in command ## Weather - Conditions: Visual (VMC), Day - Wind: 350° at 14 knots - Visibility: 10 statute miles - Lowest ceiling: 20,000 ft overcast - Temperature: 45 °F, dew point 37 °F - Altimeter: 30.00 inHg - Observed at: MOB, 27 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 19931229047439A](https://openairdocs.org/incident/19931229047439A), Dec 29, 1993: Kaman HH43BF, Mobile, AL, Substantial damage. Partial loss rotor control. Dropped logs. Autorotated to hard landing. Cotter pin teeter pin retention nut absent. 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.