# NTSB LAX00TA355: Hughes TH-55A, N331SD, Phoenix, AZ, September 29, 2000 - Type: NTSB accident investigation - Classification: Accident · No injuries · Final report - Date: September 29, 2000, 12:00 local (19:00 UTC) - Place: Phoenix, AZ - Coordinates: 33.691665, -112.082221 - Nearby events: https://openairdocs.org/map.md?lat=33.6917&lon=-112.0822&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report November 25, 2003 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 50389 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX00TA355 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/50389/pdf - Page: https://openairdocs.org/ntsb/LAX00TA355 ## Probable cause the flight instructor's misjudged flare during a simulated autorotation, which led to a hard landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Hard landing, landing - flare/touchdown - autorotation - initiated, pilot in command(cfi) - misc rotorcraft,main rotor/tail boom contact - flare - misjudged, pilot in command(cfi) (cause) ## Analysis The single engine helicopter experienced a main rotor-tail boom strike at the termination of a practice autorotation. The flight instructor reported that he was demonstrating a 180-degree practice autorotation, and said that the entry, airspeed, rate of descent, deceleration, flare, and touchdown were normal. After touchdown he estimated that there was a ground slide of about 5 to 8 feet. As the aircraft stopped, he heard a loud sharp sound that was accompanied by sustained vibration and an uncommanded right yaw of about 30 degrees. After he and the student exited the helicopter, he noted that the main rotor blades had contacted the tail boom, damaging the tail rotor drive shaft, tail boom, as well as all the main rotor and tail rotor blades. The flight instructor stated that he did not perceive any action or inaction on his part that could be construed as detrimental to the safe outcome of the maneuver. According to the FAA inspector, who responded to the accident site and examined the helicopter, there were no signs of mechanical problems that would have contributed to the accident. The flight instructor had accumulated approximately 1,320 hours of helicopter flight time, of which approximately 800 hours were obtained in the same make and model as the accident helicopter. ## Factual narrative On September 29, 2000, at 1200 mountain standard time, a Hughes TH-55A single engine helicopter, N331SD, experienced a main rotor-tail boom strike at the termination of a practice autorotation at Phoenix-Deer Valley Municipal Airport (DVT), Phoenix, Arizona. The helicopter sustained substantial damage; however, the certificated flight instructor and the airplane-rated student were not injured. The helicopter was registered to and operated by the Maricopa County Sheriff's Office as a public-use instructional flight under 14 Code of Federal Regulations Part 91 when the accident occurred. The flight was returning from a round robin flight that departed DVT with stops at local airports before terminating at DVT at the time of the accident. Visual meteorological conditions prevailed at the time and no flight plan had been filed. The flight instructor reported that he was demonstrating a 180-degree practice autorotation in the north traffic pattern. He said that the entry, airspeed, rate of descent, deceleration, flare, and touchdown were normal. After touchdown he estimated that there was a ground slide of about 5 to 8 feet. As the aircraft stopped, he heard a loud sharp sound that was accompanied by sustained vibration and an uncommanded right yaw of about 30 degrees. He shutdown the engine by pulling the fuel valve and mixture control into the "off" position. After he and the student exited the helicopter, he noted that the main rotor blades had contacted the tailboom, damaging the tail rotor drive shaft, tail boom, as well as all the main rotor and tail rotor blades. The flight instructor stated that he did not perceive any action or inaction on his part that could be construed as detrimental to the safe outcome of the maneuver. According to the Federal Aviation Administration inspector who responded to the accident site and examined the helicopter, there were no signs of mechanical problems that would have contributed to the accident. The flight instructor had accumulated approximately 1,320 hours of helicopter flight time, of which approximately 800 hours were obtained in the same make and model as the accident helicopter. ## Aircraft - Registration: [N331SD](https://openairdocs.org/deregistered/N331SD-2022-02-05), registration cancelled 2022-02-05, S/N 291105, built 1969 (OpenAirDocs) - Reported make and model: Hughes TH-55A - Registry model: [Schweizer TH55A/269A](https://openairdocs.org/model/schweizer-th55a-269a) (registry code 8059503) (OpenAirDocs) - Registry engine: [Lycoming HIO-360 series](https://openairdocs.org/engine/lycoming-hio-360-series) (registry code 41524, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 291105 - Airframe hours: 10746.7 - Engines: Textron Lycoming HIO-360-B1A 160 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Maricopa County - Airworthiness certificate: Standard, Normal - Last inspection: Annual, December 2, 1999, 16.1 hours before - Departed: DVT, PHOENIX, AZ - Destination: DVT, Phoenix, AZ - Airport: DVT, Phoenix Deer Valley ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 39; injuries: none; airline transport, flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; last flight review May 30, 1999; seat: left; flight hours: 6,365 total, 800 in this make and model, 6,230 as pilot in command, 35 in the last 90 days, 25 in the last 30 days, 5 in the last 24 hours - Student pilot; age 37; injuries: none; commercial; airplane ratings: single-engine land, multi-engine land; medical: class 2, valid medical--no waivers/lim.; last flight review March 26, 2000; seat: right; flight hours: 1,978 total, 54 in this make and model, 1,674 as pilot in command, 103 in the last 90 days, 45 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Not reported - Wind: 140° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 97 °F, dew point 57 °F - Altimeter: 29.00 inHg - Observed at: PHX, 16 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 20000929014739A](https://openairdocs.org/incident/20000929014739A), Sep 29, 2000: Hughes TH55A, Phoenix, AZ, No damage. (-23) The second pilot said PIC landed the a/c hard and he thought that is what caused the main rotor blade to strike the tail boom. Attached info. 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.