# NTSB MIA94LA002: Schweizer 269C, N95AF, Opa-Locka, FL, October 6, 1993 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: October 6, 1993, 10:30 local (14:30 UTC) - Place: Opa-Locka, FL - Coordinates: 25.909463, -80.270149 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=25.9095&lon=-80.2701&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report September 20, 1994 - Report: Approved by Office Director - NTSB case key (mKey): 37444 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA94LA002 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/37444/pdf - Page: https://openairdocs.org/ntsb/MIA94LA002 ## Probable cause IMPROPER SERVICING OF THREE OF THE FOUR MAIN LANDING GEAR DAMPERS BY COMPANY MAINTENANCE PERSONNEL, AND INNADEQUATE REMEDIAL ACTION BY THE PILOT AS GROUND RESONANCE BEGAN. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - on ground/water, landing - landing gear,main gear shock absorbing strut - improper (cause) - maintenance - improper, company maintenance personnel (cause) - ground resonance - remedial action - inadequate, pilot in command (cause) - Airframe/component/system failure/malfunction, other - landing gear,skid assembly - overload - Roll over, other ## Analysis THE HELICOPTER WAS INVOLVED IN A PREVIOUS ACCIDENT INVOLVING A TAIL ROTOR STRIKE. AS A RESULT, IN PART, THE 4 LANDING GEAR DAMPERS WERE SERVICED. THE HELICOPTER WAS REPAIRED, INSPECTED, AND SIGNED OFF FOR RETURN TO SERVICE. TESTS OF THE MAIN ROTOR TRACK AND BALANCE WERE PERFORMED WITH NO DISCREPANCIES NOTED. THE PILOT REPORTED THAT AS HE LANDED FROM A HOVER, THE HELICOPTER BEGAN TO OSCILLATE FORE AND AFT (APPARENT GROUND RESONANCE). AT THE TIME, FULL POWER WAS APPLIED AND THE COLLECTIVE CONTROL WAS DOWN. REPORTEDLY, THE PILOT DID NOT RAISE THE COLLECTIVE. SUBSEQUENTLY, THE LEFT SKID FAILED, AND THE HELICOPTER ROLLED ONTO ITS LEFT SIDE. THREE OF THE 4 LANDING GEAR DAMPERS WERE DETERMINED TO BE IMPROPERLY SERVICED. THE MAIN ROTOR BLADE DAMPERS WERE TESTED AND WERE FOUND TO BE FREE OF PREIMPACT FAILURE OR MALFUNCTION. ## Factual narrative On October 6, 1993, about 1030 eastern daylight time, a Schweizer 269C, N95AF, registered to Helicopter Training Academy, Inc., was substantially damaged after touchdown during a maintenance test flight at the Opa-Locka Airport, Opa-Locka, Florida. Visual meteorological conditions prevailed at the time and no flight plan was filed. The commercial-rated pilot and one passenger were not injured. The flight originated about 5 minutes earlier. The pilot provided a written statement which indicates that the purpose of the flight was to track the main rotor blades. After landing from a hover, the helicopter began to oscillate fore and aft. At that time full power was applied and the collective control was down. The pilot did not raise the collective control and the helicopter rolled onto its left side. He further stated that there were no discrepancies found during the track and balance procedure. The pilot initially told an FAA inspector that the helicopter landed hard on the left skid but denied this when questioned. Review of FAA records revealed that the helicopter was substantially damaged in an accident on August 18, 1993, which was investigated by the NTSB. Review of the helicopter maintenance records revealed that the helicopter was repaired following the accident including, in part, servicing of the four landing gear dampners. Two mechanics each serviced two dampners; however, the records do not indicate which dampners by serial number were serviced by whom. The four landing gear dampners were removed from the helicopter and sent to the manufacturer for Load-Stroke testing which was performed in the presence of an FAA inspector. Load- Stroke testing of the four dampners revealed that the left front "exhibited a significant overcharged condition." The right front dampner was "slightly overcharged." The left rear dampner was determined to be serviced in the proper range, and the right rear dampner was serviced "slightly low." According to a warning listed in the Service Information section, improper pressure will deteriorate the damping capabilities of the landing gear dampners. These conditions may result in ground resonance and destruction of the helicopter. The main rotor blade dampners were also removed and sent to the manufacturer for examination in the presence of an FAA inspector. Examination of the dampners revealed no evidence of preimpact failure or malfunction. ## Aircraft - Registration: [N95AF](https://openairdocs.org/deregistered/N95AF-2002-07-31), registration cancelled 2002-07-31, S/N S1574, built 1991 (OpenAirDocs) - Reported make and model: SCHWEIZER 269C - Registry model: [Schweizer 269C](https://openairdocs.org/model/schweizer-269c) (registry code 8059502) (OpenAirDocs) - Registry engine: [Lycoming HIO-360 series](https://openairdocs.org/engine/lycoming-hio-360-series) (registry code 41524, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: S1574 - Airframe hours: 378 - Engines: LYCOMING HIO-360-D1A 190 horsepower reciprocating - Damage: Substantial damage - Flight: Part 91 - Operator: Miami Helicopter Service, Inc. - Registered owner: Helicopter Training Academy - Airworthiness certificate: Standard, Normal - Last inspection: Annual, September 29, 1993 - Departed: OPF - Destination: OPF - Airport: OPF, Opa-Locka ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 30; commercial; instrument ratings: helicopter; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 904 total, 74 in this make and model, 50 in the last 90 days, 41 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 130° at 7 knots - Visibility: 12 statute miles - Lowest ceiling: 10,000 ft broken - Altimeter: 30.00 inHg - Observed at: OPF, 1 nm away ## Other investigations on N95AF (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 MIA93LA177](https://openairdocs.org/ntsb/MIA93LA177), Aug 18, 1993: Schweizer 269C (N95AF), Punta Gorda, FL, substantial damage. Probable cause: THE PILOT-IN-COMMAND'S IMPROPER USE OF THE FLIGHT CONTROLS (CYCLIC AND COLLECTIVE PITCH) DURING A SIMULATED AUTOROTATION WITH TURN, RESULTING IN AN IN FLIGHT COLLISION WITH TERRAIN WITH THE TAIL SKID… 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.