# NTSB LAX95LA136: Hughes 269A, N8873F, Van Nuys, CA, March 16, 1995 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: March 16, 1995, 10:57 local (18:57 UTC) - Place: Van Nuys, CA - Coordinates: 34.18962, -118.490394 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.1896&lon=-118.4904&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report September 24, 1995 - Report: Approved by Office Director - NTSB case key (mKey): 29056 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX95LA136 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/29056/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=29056 - Page: https://openairdocs.org/ntsb/LAX95LA136 ## Probable cause the operation of the helicopter with improper adjustment of the landing gear and main rotor dampers due to the inadequate maintenance inspection of the helicopter by maintenance personnel and an inadequate preflight inspection by the pilot. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Roll over, landing - flare/touchdown - rotor system,main rotor hub lead-lag stop/damper - pressure too low (cause) - landing gear,main gear shock absorbing strut - pressure too low (cause) - maintenance,inspection - inadequate, other maintenance personnel (cause) - aircraft preflight - inadequate, pilot in command (cause) - ground resonance - encountered, pilot in command ## Analysis THE PILOT ENCOUNTERED GROUND RESONANCE AFTER LANDING. THE HELICOPTER HAD TOUCHED DOWN LIGHTLY ON ITS LANDING GEAR SYSTEM AND BEGAN TO OSCILLATE FROM SIDE TO SIDE. THE HELICOPTER CONTINUED TO OSCILLATE UNTIL ONE SIDE OF THE HELICOPTER LANDING GEAR STRUCTURE FAILED. THE HELICOPTER THEN ROLLED ON ITS SIDE. THE FOUR LANDING GEAR DAMPERS AND TWO MAIN ROTOR DAMPERS WERE FOUND OUT OF LIMITS. THE ACCIDENT FLIGHT WAS THE FIRST FLIGHT AFTER A 50-HOUR INSPECTION WAS PERFORMED. DURING THE INSPECTION, THE LANDING GEAR DAMPERS SHOULD HAVE BEEN CHECKED FOR PROPER EXTENSION. THE LANDING GEAR AND MAIN ROTOR DAMPERS SHOULD ALSO BE CHECKED BY THE PILOT DURING HIS PREFLIGHT PREPARATION OF THE HELICOPTER. ## Factual narrative On March 16, 1995, at 1057 hours Pacific standard time, a Hughes 269A, N8873F, encountered ground resonance after landing at the Van Nuys Airport, Van Nuys, California. The certificated private pilot received minor injuries. The helicopter was destroyed. The helicopter was being operated by the pilot/owner as a solo instructional flight. Visual meteorological conditions prevailed. Witnesses reported to Federal Aviation Administration (FAA) inspectors that the helicopter had touched down lightly on its landing gear system and began to oscillate from side to side. The helicopter continued to oscillate until one side of the helicopter landing gear structure collapsed. The helicopter then rolled on its side. According to the FAA, the pilot holds a private pilot certificate with ratings for single- and multiengine airplanes. The pilot was pursuing a helicopter rating and was conducting a solo flight under the supervision of a certified flight instructor. The pilot had accrued about 60 hours of flight experience in helicopters, of which 1.7 hours were on the accident flight. The four landing gear dampers and three main rotor dampers were sent to manufacturer facilities for testing. According to the manufacturer, the four landing gear dampers and two of the three main rotor dampers were found out of limits. A copy of the manufacturer's report is attached as part of this report. A 50-hour inspection was accomplished by an airframe and powerplant mechanic on March 3, 1995, about 1.7 flight hours before the accident. The handbook of maintenance instructions for the helicopter details specific inspection items during the 50-hour inspection. The first item on the inspection checklist indicates a daily inspection should be performed as part of the 50-hour inspection. During the daily inspection, the landing gear dampers are checked for proper extension. The Handbook of Maintenance Instructions instructs maintenance personnel to check and service landing gear dampers during a daily inspection. The handbook also states, "ground resonance can result if helicopter is operated when the damper extension, type of oil, and/or oil-to-air ratio in the damper is incorrect." The landing gear and main rotor dampers are also part of the pilot preflight inspection of the helicopter. ## Aircraft - Registration: [N8873F](https://openairdocs.org/deregistered/N8873F-1998-01-08), registration cancelled 1998-01-08, S/N 630241 (OpenAirDocs) - Reported make and model: HUGHES 269A - Registry model: [Hughes 269A](https://openairdocs.org/model/hughes-269a) (registry code 4470402) (OpenAirDocs) - Category: Helicopter - Serial number: 63-0241 - Airframe hours: 3144 - Engines: LYCOMING HIO-360-B1A 180 horsepower reciprocating - Damage: Destroyed - Flight: Instructional, Part 91 - Registered owner: James D. Layland - Airworthiness certificate: Standard, Normal - Last inspection: Continuous airworthiness, March 30, 1995, 2 hours before - Departed: VNY, CA - Airport: VNY, Van Nuys ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 49; private; airplane ratings: single-engine land, multi-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: right; flight hours: 1,039 total, 60 in this make and model, 924 as pilot in command ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 20 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 54 °F - Altimeter: 29.00 inHg - Observed at: VNY, 1 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 19950316004119A](https://openairdocs.org/incident/19950316004119A), Mar 16, 1995: Hughes 269A, Van Nuys, CA, Destroyed. Student touched skid lightly landing. Began oscillations until skid collapsed. Skid gear dampers out of adjustment. ## Other investigations on N8873F (4) 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 FTW82FPJ15](https://openairdocs.org/ntsb/FTW82FPJ15), Jul 17, 1982: Hughes 269 (N8873F), Boise City, OK, substantial damage - [NTSB MKC760CQ73](https://openairdocs.org/ntsb/MKC760CQ73), Aug 7, 1976: Hughes 269A (N8873F), Alden, KS, substantial damage - [NTSB CHI68F0016](https://openairdocs.org/ntsb/CHI68F0016-109462), Jun 4, 1968: Hughes 269A (N8873F), Richmond, IL, substantial damage - [NTSB UNK64X3187](https://openairdocs.org/ntsb/UNK64X3187), Aug 2, 1964: Hughes 269A (N8873F), Buffalo, NY, substantial damage ## Docket (7 files) The files NTSB released with the investigation on August 4, 1995, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=29056. 6.5 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 296 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40441125&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Maintenance Records (item 2, .PDF, 50 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40441126&FileExtension=.PDF&FileName=Maintenance%20Records-Redacted.PDF - Ground Resonance Information (item 3, .PDF, 153 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40025199&FileExtension=.PDF&FileName=Ground%20Resonance%20Information-Master.PDF - Helicopter Inspection Requirements (item 4, .PDF, 305 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40441127&FileExtension=.PDF&FileName=Helicopter%20Inspection%20Requirements-Redacted.PDF - Schweizer Aircraft Report of Examination (item 5, .PDF, 5.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40441128&FileExtension=.PDF&FileName=Schweizer%20Aircraft%20Report%20of%20Examination-Redacted.PDF - Statement of Party Representatives to NTSB Investigation (item 6, .PDF, 61 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40441129&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 7, .PDF, 44 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40441130&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-Redacted.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.