# NTSB ANC06LA038: MD Helicopters MD 900, N912LH, Mesa, AZ, March 22, 2006 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: March 22, 2006, 16:00 local (23:00 UTC) - Place: Mesa, AZ - Coordinates: 33.460834, -111.728332 - Nearby events: https://openairdocs.org/map.md?lat=33.4608&lon=-111.7283&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report October 31, 2006 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: Phoenix FSDO - NTSB case key (mKey): 63419 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC06LA038 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/63419/pdf - Page: https://openairdocs.org/ntsb/ANC06LA038 ## Probable cause The manufacturer's inadequate design clearance of the main rotor blade grip pitch cases, which resulted in damage to the pitch cases when they contacted main rotor perimeter bolts during maneuvering flight. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, maneuvering - acft/equip,inadequate control shape/size, manufacturer (cause) - rotor system,main rotor hub grip(sleeve) - scored (cause) - rotor system,main rotor hub grip(sleeve) - clearance ## Analysis The experimental category flight was being operated by the helicopter manufacturer under Title 14, CFR Part 91, when the accident occurred. The commercial certificated helicopter pilot was conducting a series of climbing and descending turns while a second helicopter, flying alongside, filmed the maneuvers. According to a safety representative for the helicopter manufacturer, all of the maneuvers were conducted within the normal limitations of the helicopter. The maneuvers were completed uneventfully, with no in-flight anomalies noted, and the helicopter returned to the manufacturer's base. While conducting a routine daily inspection of the helicopter in preparation for the next scheduled flight, maintenance technicians discovered damage to the main rotor hub's five pitch case assemblies, slightly aft of the upper damper cap. The damage was a result of the pitch cases striking the upper main rotor hub perimeter bolts. All five pitch cases were damaged beyond repairable limits, and were replaced. The safety representative for the helicopter manufacturer reported that the anticipated corrective action will be to increase the clearance between the pitch cases and the main rotor hub perimeter bolts by trimming additional material from the inboard and upper portion of the main rotor pitch case assemblies during the manufacturing process. ## Factual narrative On March 22, 2006, about 1600 mountain standard time, an MD Helicopters MD 900 helicopter, N912LH, owned and operated by MD Helicopters, Inc., Mesa, Arizona, sustained substantial damage while maneuvering near Mesa. The commercial certificated pilot and one crewman were not injured. The experimental category flight was being operated as an air-to-air photographic flight under Title 14, CFR Part 91, when the accident occurred. Visual meteorological conditions prevailed at the time of the accident, and company flight following procedures were in effect. The local area flight originated at the Falcon Field Airport, Mesa, about 1530. A postflight inspection of the helicopter disclosed damage to all five of the main rotor hub pitch cases. During a telephone conversation with the National Transportation Safety Board investigator-in-charge on March 28, an aviation safety representative for MD Helicopters reported that the purpose of the flight was to photograph the accident helicopter during flight. During the flight, the pilot of the accident helicopter was required to maneuver the helicopter through a series climbing and descending turns while a second helicopter, flying alongside, filmed the maneuvers. The safety representative reported that all of the maneuvers were conducted within the normal limitations of the helicopter. All of the maneuvers were completed uneventfully, with no in-flight anomalies noted, and the helicopter returned to the MD Helicopters facility in Mesa. According to the safety representative, on March 23, while conducting a routine daily inspection of the helicopter in preparation for flight, maintenance technicians discovered damage to the main rotor hub's five pitch case assemblies. He said that the damage to each main rotor hub pitch case was limited to the upper inboard lip, slightly aft of the upper damper cap. He described the impact damage as a result of the pitch cases striking the upper main rotor hub perimeter bolts. All five pitch cases were damaged beyond repairable limits, and were subsequently replaced. In the NTSB Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1) submitted on behalf of MD Helicopters, the safety representative reported that following this event, the anticipated corrective action will be to increase the clearance between the pitch cases and the main rotor hub perimeter bolts by trimming additional material from the inboard and upper portion of the main rotor pitch case assemblies during the manufacturing process. ## Aircraft - Registration: [N912LH](https://openairdocs.org/aircraft/N912LH), registered now, S/N 900-00095, built 2001 (OpenAirDocs) - Reported make and model: MD Helicopters, Inc. MD 900 - Registry model: [MD Helicopters MD 900](https://openairdocs.org/model/md-helicopters-md-900) (registry code 3030004) (OpenAirDocs) - Registry engine: [Pratt & Whitney Canada PW207E](https://openairdocs.org/engine/pratt-whitney-canada-pw207e) (registry code 52161, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 900-00095 - Airframe hours: 77.04 - Engines: Pratt & Whitney Canada PW207E 18400 horsepower turbo shaft - Damage: Substantial damage - Flight: Other work use, Part 91 - Registered owner: MD Helicopters, Inc. - Airworthiness certificate: Special, Experimental (Special) - Last inspection: 100 hour, January 1, 2006 - Departed: FFZ, MESA, AZ - Destination: FFZ, Mesa, AZ - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 45; injuries: none; flight instructor, commercial; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 2, without waivers/limitations; seat: right; flight hours: 11,266 total, 1,017 in this make and model, 10,801 as pilot in command, 146 in the last 90 days, 25 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: variable at 10 knots - Visibility: 20 statute miles - Lowest ceiling: none - Temperature: 63 °F ## 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 20060322005049A](https://openairdocs.org/incident/20060322005049A), Mar 22, 2006: Doug MD900, Mesa, AZ, Substantial damage. (-23) During a photo flight northeast of the Mesa ffz, with the pilot and crew chief aboard, the main rotor pitch cases were damaged by contact with the… 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.