# NTSB MIA97LA103: Hughes TH-55, N818D, Cullman, AL, March 28, 1997 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: March 28, 1997, 16:45 local (22:45 UTC) - Place: Cullman, AL - Coordinates: 34.169769, -86.829269 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.1698&lon=-86.8293&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 2 serious - Status: Completed, report April 10, 1998 - Report: Approved by Office Director - NTSB case key (mKey): 38233 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA97LA103 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/38233/pdf - Page: https://openairdocs.org/ntsb/MIA97LA103 ## Probable cause a loss of engine power for undetermined reasons and the pilot-in-command's failure to maintain control of the helicopter. Factors in this accident were: an improper autorotation as a result of improper collective use and resulting failure to maintain main rotor rpm. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, maneuvering - reason for occurrence undetermined (cause) - Forced landing, emergency descent/landing - In flight collision with terrain/water, emergency descent/landing - aircraft control - not maintained, pilot in command(cfi) (cause) - autorotation - improper, pilot in command(cfi) (contributing factor) - rotor rpm - not maintained, pilot in command(cfi) (contributing factor) ## Analysis The flight instructor and student pilot remained in closed traffic in order to perform practice maneuvers and emergency procedure training to include autorotations. Witnesses saw the helicopter take off to the west and turn immediately to the right, climb to an altitude of 30 feet above ground level (AGL), and attain an estimated forward airspeed of 20 to 30 knots. The helicopter was then observed in a descent and disappear out of view before the witnesses heard the sound of impact with the ground. Several of the witnesses stated that just prior to impact they heard what sounded like the engine overspeed, and then cut off. The helicopter landed near a telephone pole and support lines. There was no evidence found to indicate that the helicopter contacted the pole or the lines. According to the first people to arrive at the crash site, the student pilot did not know what had happened. The CFI said, 'we had been flying for about an hour. We'd finished our training and were heading back with...[the student] on the controls, when the engine quit. I said I've got it and took the controls, but we were too low, with no time to recover, and crashed.' Examination of the wreckage revealed that the main and tail rotor RPM was low at impact,' because the rotor blades showed little damage. In addition, the engine and airframe examinations revealed no discrepancies. Several attempts were made to talk to the CFI at the hospital to get his factual account of the accident, but all attempts to interview him were unsuccessful. The NTSB Form 6120.1/2, was returned without a statement from the CFI. ## Factual narrative On March 28, 1997, about 1645 central standard time, a Hughes TH-55 helicopter, N818D, registered to a private owner, crashed while maneuvering at a low altitude near Cullman, Alabama. Visual meteorological conditions prevailed at the time and no flight plan was filed for the Title 14 CFR Part 91 local instructional flight. The commercial-rated pilot/certified flight instructor (CFI) and student pilot received serious injuries. The helicopter was substantially damaged. The flight originated about 1 hour before the accident. The flight had remained in closed traffic at Folsom Field, in order for the pilots to perform practice maneuvers and emergency procedure training, to include autorotations. Witnesses saw the helicopter takeoff to the west, and turn immediately to the right, climb to an altitude of 30 feet above ground level (AGL), and attain an estimated forward airspeed of 20 to 30 knots. The helicopter was observed in an almost vertical descent, and disappear out of view of the witnesses, before they heard the sound of impact with the ground. One of the witnesses stated that just prior to impact, "...I heard what sounded like the helicopter doing a hovering autorotation, the engine sounded like it over speeded then cut...." Other witnesses also said they had heard what sounded like an overspeed before impact. According to investigators that were at the crash site, ground scars indicated that the helicopter impacted on heading of 040 degrees, with little to no forward movement. The helicopter landed near a telephone pole and support lines. There was no evidence found to indicate that the helicopter contacted the pole or the lines. The first people to arrive at the crash site said that both pilots were alive, and the student pilot said he did not know what had happened. The CFI said, "we had been flying for about an hour. We'd finished our training and were heading back with...[the student] on the controls, when the engine quit. I said I've got it and took the controls, but we were too low, with no time to recover, and crashed." According to the FAA inspector's statement, there was evidence found at the crash site "indicating low main and tail rotor RPM at impact," because the rotor blades showed little damage. In addition, the engine examination revealed no discrepancies. The FAA concluded that "the engine was running at impact." The helicopter examination revealed control continuity on all flight controls and no discrepancies were found with the helicopter. Several attempts were made to talk to the CFI at the hospital to get his factual account of the accident, but all attempts to interview him were unsuccessful. The NTSB Form 6120.1/2, was returned without a statement from the CFI. ## Aircraft - Registration: [N818D](https://openairdocs.org/deregistered/N818D-2013-03-26), registration cancelled 2013-03-26, S/N 6716818, built 1967 (OpenAirDocs) - Reported make and model: Hughes TH-55 - Registry model: [Hughes TH-55](https://openairdocs.org/model/hughes-th-55) (registry code 4471002) (OpenAirDocs) - Registry engine: [Lycoming HIO-360 series](https://openairdocs.org/engine/lycoming-hio-360-series) (registry code 41524, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 6716818 - Airframe hours: 12489 - Engines: Lycoming HIO-360-B1A 180 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Joe Green - Airworthiness certificate: Standard, Normal - Last inspection: Annual, October 8, 1996, 99 hours before - Departed: 3A1 - Airport: 3A1, Cullman ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 49; commercial, flight instructor; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 1,287 total ## Weather - Conditions: Visual (VMC), Day - Wind: 220° at 16 knots, gusting 20 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 79 °F, dew point 64 °F - Altimeter: 29.00 inHg - Observed at: HTV, 22 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 19970328003999A](https://openairdocs.org/incident/19970328003999A), Mar 28, 1997: Hughes TH55A, Cullman, AL, Substantial damage. Engine quit near airport. Too low and slow for autorotation according to CFI. Shos engine running. Rotor decay. (-23) on March 28, 1997 at 16:45 CST a Hughes… 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.