# NTSB CEN12LA247: Hughes 269A, N69HJ, Grinnell, IA, April 17, 2012 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 17, 2012, 11:16 local (16:16 UTC) - Place: Grinnell, IA - Coordinates: 41.709999, -92.736114 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.7100&lon=-92.7361&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Ground resonance](https://openairdocs.org/ntsb-events/232) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report August 13, 2013 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 83415 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN12LA247 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/83415/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=83415 - Page: https://openairdocs.org/ntsb/CEN12LA247 ## Probable cause The pilot's improper liftoff technique, which resulted in ground resonance, and the pilot's delayed recognition of the ground resonance. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Action: incorrect action performance](https://openairdocs.org/ntsb-findings/02041015): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Hughes 269A, 1 case](https://openairdocs.org/ntsb-findings/02041015/cases.md?model=4470402), [All aircraft, 1,386 cases](https://openairdocs.org/ntsb-findings/02041015/cases.md) - [Aircraft](https://openairdocs.org/ntsb-findings/01060000): Aircraft › Aircraft oper/perf/capability · Not specified (probable cause); cases with it: [Hughes 269A, 1 case](https://openairdocs.org/ntsb-findings/01060000/cases.md?model=4470402), [All aircraft, 63 cases](https://openairdocs.org/ntsb-findings/01060000/cases.md) - [Info processing/decision: identification/recognition](https://openairdocs.org/ntsb-findings/02041510): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Hughes 269A, 1 case](https://openairdocs.org/ntsb-findings/02041510/cases.md?model=4470402), [All aircraft, 559 cases](https://openairdocs.org/ntsb-findings/02041510/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Takeoff: Ground resonance](https://openairdocs.org/ntsb-events/232) (defining event); cases with it: [Hughes 269A, 3 cases](https://openairdocs.org/ntsb-events/232/sequence.md?model=4470402), [All aircraft, 21 cases](https://openairdocs.org/ntsb-events/232/sequence.md) - [Takeoff: Attempted remediation/recovery](https://openairdocs.org/ntsb-events/060); cases with it: [Hughes 269A, 2 cases](https://openairdocs.org/ntsb-events/060/sequence.md?model=4470402), [All aircraft, 1,422 cases](https://openairdocs.org/ntsb-events/060/sequence.md) - [Takeoff-rejected takeoff: Aircraft structural failure](https://openairdocs.org/ntsb-events/337); cases with it: [Hughes 269A, 1 case](https://openairdocs.org/ntsb-events/337/sequence.md?model=4470402), [All aircraft, 290 cases](https://openairdocs.org/ntsb-events/337/sequence.md) ## Analysis The helicopter began to vibrate as the pilot raised the collective for liftoff. The pilot lowered the collective and closed the throttle when the vibration began; however, he was too late in recognizing the onset of ground resonance, which resulted in a violent, uncontrollable oscillation and separation of the tail boom from the fuselage. Examination of the helicopter revealed no anomalies that would have precluded normal operation. ## Factual narrative On April 17, 2012, about 1116 central daylight time, a Hughes 269A, N69HJ, experienced ground resonance during takeoff at Grinnell Regional Airport (GGI), Grinnell, Iowa. The pilot subsequently aborted the takeoff. The commercial pilot and a passenger were uninjured. The helicopter sustained substantial damage to the fuselage. The helicopter was registered to Lowry Flying Service Inc and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed and a flight plan had not been filed for the local flight that was originating at the time of the accident. The pilot stated that when he raised the collective for liftoff, the helicopter started to vibrate. He "rolled the collective down" and "throttle off," but it was too late, and the helicopter shook apart "immediately." The transmission broke severing the tail. The rotor blades hit the ground. According to the Federal Aviation Administration inspector, the helicopter never lifted off the ground during the accident flight. The pilot experienced ground resonance on three previous flights, the first of which was during takeoff and the other two occurred during landing. During the previous three occurrences of ground resonance, the pilot was able to identify and initiate a successful recovery. During the accident flight, the pilot was too late in recognizing the onset of ground resonance. There were no mechanical anomalies that would have precluded normal operation. ## Aircraft - Registration: [N69HJ](https://openairdocs.org/deregistered/N69HJ-2021-03-27), registration cancelled 2021-03-27, S/N 580869 (OpenAirDocs) - Reported make and model: HUGHES 269A (UNDESIGNAT) - Registry model: [Hughes 269A](https://openairdocs.org/model/hughes-269a) (registry code 4470402) (OpenAirDocs) - Category: Helicopter - Serial number: 580869 - Airframe hours: 3085 - Engines: Lycoming HIO-360-B1A 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Pilot - Registered owner: Lowry Flying Service Inc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 6, 2012 - Departed: GGI, Grinnell, IA - Destination: GGI, Grinnell, IA - Airport: GGI, Grinnell Regional Airport ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 59; injuries: none; airline transport, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review January 19, 2011; seat: right; flight hours: 8,692 total, 30 in this make and model, 30 in the last 90 days, 4 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 150° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 55 °F, dew point 37 °F - Altimeter: 30.35 inHg - Observed at: GGI ## 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 20120417005669A](https://openairdocs.org/incident/20120417005669A), Apr 17, 2012: Hughes 269A, Grinnell, IA, Substantial damage. The accident happened during the takeoff phase of flight. The pilot stated that he completed his preflight inspection and engine runup and was about to depart… ## Docket (2 files) The files NTSB released with the investigation on May 30, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=83415. 997 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 974 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40386523&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Record of Conversation (item 2, .PDF, 23 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40386526&FileExtension=.PDF&FileName=Record%20of%20Conversation-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.