# NTSB CHI97LA306: Bell 47, N9005T, Pipestone, MN, September 30, 1997 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: September 30, 1997, 14:45 local (19:45 UTC) - Place: Pipestone, MN - Coordinates: 43.999435, -96.309555 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=43.9994&lon=-96.3096&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report November 17, 1999 - Report: Approved by Office Director - NTSB case key (mKey): 10713 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI97LA306 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/10713/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=10713 - Page: https://openairdocs.org/ntsb/CHI97LA306 ## Probable cause the fracture of the pitch control rod assembly. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, maneuvering - rotorcraft flight control,pitch change rod/link - fractured - Loss of control - in flight, maneuvering - rotorcraft flight control,pitch change rod/link - fractured (cause) - In flight collision with terrain/water, maneuvering - terrain condition - ground ## Analysis The pilot stated that while he was ferrying the helicopter to the next field he, 'heard a loud bang from behind.' He said that the cyclic control, 'jerked,' the helicopter began to vibrate, and the rotor RPM decreased. He increased the throttle, but the engine responded as if there was no load on the engine. He initiated autorotation, but was unable to regain control, and the aircraft impacted the terrain. Post accident investigation revealed that one of two pitch control rod assemblies had fractured between the clevis and turnbuckle. Examination of the fracture showed areas of fatigue striations and multiple crack initiation sites on the machined surface. ## Factual narrative On September 30, 1997, at 1445 central daylight time, a Bell 47, N9005T, registered to Aerial Blades, Inc., of Flandreau, South Dakota, piloted by a commercial pilot, impacted the terrain, while positioning the aircraft for an aerial application mission. The helicopter was substantially damaged. The pilot reported serious injuries. The local 14 CFR Part 137 flight was operating in visual meteorological conditions. No flight plan was on file. The flight originated from a farm field in Pipestone, Minnesota, exact time unknown. The pilot stated, in an interview with the Federal Aviation Administration, that while he was ferrying the helicopter to the next field he, "heard a loud bang from behind." The pilot stated that the cyclic control, "jerked," helicopter began to vibrate, and rotor RPM decreased. The pilot stated that he increased the throttle, but the engine responded as if there was no load on the engine. The pilot initiated autorotation, but was unable to regain control, and the aircraft impacted the terrain. Post accident investigation revealed that one of two pitch control rod assemblies had fractured between the clevis and turnbuckle. The Material Laboratory Division of the National Transportation Safety Board, Washington D.C., examined the fractured control rod assembly. Examination of the fracture showed areas of fatigue striations and multiple crack initiation sites on the machined surface. For additional information, see attached Material Laboratory Factual Report. ## Aircraft - Registration: [N9005T](https://openairdocs.org/aircraft/N9005T), registered now, S/N CCI-74-1, built 1974 (OpenAirDocs) - Reported make and model: Bell 47 - Registry model: [Continental Copters TOMCAT MK5A](https://openairdocs.org/model/continental-copters-tomcat-mk5a) (registry code 2390101) (OpenAirDocs) - Registry engine: [Lycoming VO-435 series](https://openairdocs.org/engine/lycoming-vo-435-series) (registry code 41525, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: CCI-74-1 - Engines: Lycoming VO-435 260 horsepower reciprocating - Damage: Substantial damage - Fire: On-Ground - Flight: Aerial application, Part 137 - Registered owner: Aerial Blades, Inc. - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, April 29, 1997, 367 hours before ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 29; commercial; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: center; flight hours: 2,600 total, 30 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 260° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 37 °F - Altimeter: 30.00 inHg - Observed at: PQN ## 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 19970930029419A](https://openairdocs.org/incident/19970930029419A), Sep 30, 1997: Ccoptr TOMCATMK5A, Pipestone Count, MN, Substantial damage. Collided with ground during ag operations. (.4) the pilot stated that while he was ferrying the helicopter to the next field he, `heard a loud bang from… ## Other investigations on N9005T (2) 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 CEN18LA300](https://openairdocs.org/ntsb/CEN18LA300), Jul 27, 2018: Continental Copters Tomcat MK5A (N9005T), Le Sueur, MN, substantial damage. Probable cause: The pilot's inadequate preflight and in-flight fuel planning, during which he did not visually check the fuel quantity in the fuel tanks and instead relied on the fuel gauges that were showing… - [NTSB CEN13LA537](https://openairdocs.org/ntsb/CEN13LA537), Sep 6, 2013: Continental Copters Tomcat MK5A (N9005T), Arlington, MN, substantial damage. Probable cause: The pilot’s failure to maintain control of the helicopter while maneuvering when he removed his hand from the collective control while plugging in his radio connection to his helmet, which resulted… ## Docket (2 files) The files NTSB released with the investigation on April 19, 1999, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=10713. 1.3 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 378 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40413138&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Materials Laboratory Factual Report (item 2, .PDF, 903 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40104323&FileExtension=.PDF&FileName=Materials%20Laboratory%20Factual%20Report%20-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.