# NTSB WPR09LA253: Gauchat Safari, N147MD, Rock Springs, AZ, May 22, 2009 - Type: NTSB accident investigation - Classification: Accident · Fatal · Limited investigation · Final report - Date: May 22, 2009, 13:30 local (20:30 UTC) - Place: Rock Springs, AZ - Coordinates: 34.042499, -112.149444 - Nearby events: https://openairdocs.org/map.md?lat=34.0425&lon=-112.1494&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) - Highest injury: Fatal - Injuries: 2 fatal - Status: Completed, report June 27, 2011 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Adminstration - NTSB case key (mKey): 73884 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR09LA253 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/73884/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=73884 - Page: https://openairdocs.org/ntsb/WPR09LA253 ## Probable cause The separation of the main rotor head during cruise flight as a result of cyclic fatigue of the main rotor head spindle. The fatigue crack was due to an inadequate manufacturing process. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Main rotor system: main rotor head system](https://openairdocs.org/ntsb-findings/01046220): Aircraft › Aircraft propeller/rotor · Fatigue/wear/corrosion (probable cause) - [Manufacture/production](https://openairdocs.org/ntsb-findings/04013000): Organizational issues › Development · Manufacturer (probable cause) ## Analysis During a personal flight the experimental helicopter experienced an in-flight separation of the main rotor head. Both main rotor blades were located in opposite directions from the main wreckage. The helicopter was substantially damaged by the impact forces and the postimpact fire. Postaccident examination of the main rotor head assembly and the main rotor spindle revealed that the main rotor spindle had failed due to cyclic fatigue. The origin area was located near distinct circumferential machining marks. The manufacturer subsequently issued a mandatory inspection bulletin requiring inspection of all main rotor spindles. ## Factual narrative HISTORY OF FLIGHT On May 22, 2009, about 1330 mountain standard time (MST), an experimental homebuilt helicopter, Gauchat Safari, N147MD, impacted terrain near Rock Springs, Arizona, following the separation of both of the main rotor blades. The builder/pilot was operating the helicopter under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The private pilot and one passenger were fatally injured; impact forces and the post crash fire substantially damaged the helicopter. The local personal flight departed Rock Springs about 1325, with a planned destination of Phoenix, Arizona. Visual meteorological conditions prevailed, and no flight plan had been filed. Witnesses reported that the helicopter had just departed from a parking lot .3 nautical miles north of the accident site. They observed the helicopter flying southbound parallel to highway 17, when one of the main rotor blades departed the helicopter. The helicopter then fell to the ground. PERSONNEL INFORMATION No personal flight records were located for the pilot. The National Transportation Safety Board investigator-in-charge (IIC) obtained the aeronautical experience listed in this report from a review of the Federal Aviation Administration (FAA) airmen medical records on file in the Airman and Medical Records Center located in Oklahoma City, Oklahoma. The pilot reported on his medical application dated May 5, 2008, that he had a total time of 270 hours, with 50 hours logged in the last 6 months. AIRCRAFT INFORMATION The experimental homebuilt helicopter, a Gauchat Safari, serial number 2129, was issued a special airworthiness certificate on May 30, 2006. A review of the helicopter’s logbooks revealed that the helicopter had a total airframe time of 237.3 hours at the last conditional inspection dated May 10, 2009. WRECKAGE AND IMPACT INFORMATION An inspector from the FAA responded to the scene. The accident site consisted of the helicopter's fuselage, tailboom, and tail rotor system. The debris field contained both main rotor blades; one blade was located 620 feet northwest of the main wreckage, and the second blade was located 300 feet east of the main wreckage. One of the push pull control tubes was found 170 feet northwest of the main wreckage, and an operating handheld Global Position Satellite unit was located 100 feet northwest on the main wreckage. MEDICAL AND PATHOLOGICAL INFORMATION The Maricopa County Coroner completed an autopsy on the pilot May 26, 2009. The cause of death was determined to be as a result of blunt force injuries. The FAA Civil Aerospace Medical Institute (CAMI), Oklahoma City, Oklahoma, performed toxicological testing of specimens of the pilot. Analysis of the specimens contained no findings for carbon monoxide, cyanide, and volatiles. The report contained the following findings for tested drugs: 0.101 (ug/ml, ug/g) Doxylamine detected in blood, Doxylamine detected in liver. TESTS AND RESEARCH Investigators examined the wreckage at AirTransport, Phoenix, on June 29, 2009, and on August 14, 2010. Portions of the main rotor head were shipped to the NTSB materials laboratory in Washington, D.C., for further examination. The materials specialist found that the main rotor head spindle had failed in fatigue that initiated in machining marks at a radius located at the intersection of the bearing diameter with the larger inboard diameter normally obscured by the grip nut. The full report is in the public docket. ADDITIONAL INFORMATION Because of this accident and the ensuing investigation, the manufacturer issued the mandatory inspection bulletin MI-002. The bulletin requires inspection of the Main Rotor Spindle for distinct machining marks of irregular depth. In addition, any spindle which has been subjected to shock loads resulting from any accident of sufficient force to cause damage to other areas of the helicopter, re-engagement of the clutch while the rotor blades are still in motion, hard starts of the engine, over-torque of the castle nut, or repeated over speed of the main rotor head should be inspected. A copy of the mandatory inspection bulletin is located in the public docket. According to FAA Advisory Circular AC 20-27F, Certification and Operation of Amateur-Built Aircraft, "Amateur builders are free to develop their own designs or build from existing designs. We do not approve these designs and it would be impractical to develop design standards for the wide variety of design configurations, created by designers, kit manufacturers, and amateur builders." ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event) - [Enroute: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470) ## Aircraft - Registration: [N147MD](https://openairdocs.org/deregistered/N147MD-2017-04-05), registration cancelled 2017-04-05, S/N 2129, built 2006 (OpenAirDocs) - Reported make and model: GAUCHAT SAFARI - Registry model: [Gauchat Michael SAFARI](https://openairdocs.org/model/gauchat-michael-safari) (registry code 05621KH) (OpenAirDocs) - Registry engine: [Superior O-360 series](https://openairdocs.org/engine/superior-o-360-series) (registry code 59250, reciprocating) (OpenAirDocs) - Category: Helicopter, amateur-built - Serial number: 2129 - Engines: SUPERIOR XP-O-360-A3A2 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Departed: Rock Springs, AZ - Destination: Rock Springs, AZ ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 41; injuries: fatal; private; medical: class 2, without waivers/limitations; toxicology performed; flight hours: 270 total ## Weather - Conditions: Visual (VMC), Day - Wind: 330° at 3 knots - Visibility: 10 statute miles - Lowest ceiling: 7,000 ft overcast - Temperature: 72 °F, dew point 59 °F - Altimeter: 29.86 inHg - Observed at: DVT, 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 20090522011129A](https://openairdocs.org/incident/20090522011129A), May 22, 2009: Gaucha SAFARI, Rock Springs, AZ, Destroyed, 2 fatal. (-23) Witnesses reported that the helicopter had just departed from a parking lot .3 miles north of the accident site. They observed the aircraft flying south… ## Docket (7 files) The files NTSB released with the investigation on April 15, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=73884. 5.7 MB in all. - Materials Laboratory 15 - Factual Report 10-065 (item 1, .PDF, 1.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40346480&FileExtension=.PDF&FileName=Materials%20Laboratory%2015%20-%20Factual%20Report%2010-065-Master.PDF - Materials Laboratory 15 - Factual Report 10-105 (item 2, .PDF, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40345911&FileExtension=.PDF&FileName=Materials%20Laboratory%2015%20-%20Factual%20Report%2010-105-Master.PDF - Toxicological Report- Pilot (item 3, .PDF, 103 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40345881&FileExtension=.PDF&FileName=Toxicological%20Report-%20Pilot-Master.PDF - Airframe & Engine Logbook Conditional Entries (item 4, .PDF, 109 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40345887&FileExtension=.PDF&FileName=Airframe%20%26%20Engine%20Logbook%20Conditional%20Entries-Redacted.PDF - Safari Madatory Inspection Notice (item 5, .PDF, 82 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40346449&FileExtension=.PDF&FileName=Safari%20Madatory%20Inspection%20Notice-Master.PDF - Photo- Wreckage Locations (2 Embedded Photos) (item 6, .PDF, 695 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40345873&FileExtension=.PDF&FileName=Photo-%20Wreckage%20Locations%20(2%20Embedded%20Photos)-Master.PDF - Photos- FAA On-Scene Photos (6 Embedded Photos) (item 7, .PDF, 2.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40345876&FileExtension=.PDF&FileName=Photos-%20FAA%20On-Scene%20Photos%20(6%20Embedded%20Photos)-Master.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.