# NTSB ERA11LA216: Hiller UH-12E, N4033P, Culpeper, VA, March 25, 2011 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: March 25, 2011, 12:38 local (16:38 UTC) - Place: Culpeper, VA - Coordinates: 38.473888, -77.783607 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.4739&lon=-77.7836&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report November 26, 2012 - Report: Approved by Office Director - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO - NTSB case key (mKey): 78696 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA11LA216 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/78696/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=78696 - Page: https://openairdocs.org/ntsb/ERA11LA216 ## Probable cause Mechanical failure of the transmission for reasons that could not be determined because the transmission could not be torn down. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Main rotor drive](https://openairdocs.org/ntsb-findings/01046300): Aircraft › Aircraft propeller/rotor · Malfunction (probable cause); cases with it: [Hiller UH-12E, 1 case](https://openairdocs.org/ntsb-findings/01046300/cases.md?model=4360122), [All aircraft, 15 cases](https://openairdocs.org/ntsb-findings/01046300/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-low-alt flying: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) (defining event); cases with it: [Hiller UH-12E, 3 cases](https://openairdocs.org/ntsb-events/340/sequence.md?model=4360122), [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md) - [Maneuvering-low-alt flying: Loss of lift](https://openairdocs.org/ntsb-events/500); cases with it: [Hiller UH-12E, 1 case](https://openairdocs.org/ntsb-events/500/sequence.md?model=4360122), [All aircraft, 252 cases](https://openairdocs.org/ntsb-events/500/sequence.md) - [Autorotation: Hard landing](https://openairdocs.org/ntsb-events/092); cases with it: [Hiller UH-12E, 4 cases](https://openairdocs.org/ntsb-events/092/sequence.md?model=4360122), [All aircraft, 2,102 cases](https://openairdocs.org/ntsb-events/092/sequence.md) ## Analysis The aerial application flight had departed and was enroute to apply agricultural product to a nearby field; the engine rpm increased uncommanded and the pilot performed a forced landing in an open field. The pilot reported that after the helicopter came to rest, he exited and put his hand on the transmission, which was hot. He then felt the transmission cooler, which he stated was similar in temperature to the surrounding air temperature. Seven days before the accident, a continued airworthiness inspection was performed on the helicopter; the main transmission gearbox oil was drained, and the main rotor transmission was removed to facilitate engine removal. Particulate matter may have been inadvertently left in or around the main rotor transmission during its removal. During the flight the particulate matter may have become lodged in one of the journals inside the transmission and caused its failure, which then allowed the engine to overspeed and the helicopter to lose lift. However, the investigation was not able to conclusively determine the cause of the failure because the transmission could not be secured for a teardown. ## Factual narrative On March 25, 2011, at 1238 eastern daylight time, a Hiller UH-12E helicopter, N4033P, operated by Kritter Cropdusting, Inc., was substantially damaged during a forced landing following an uncommanded high engine rpm and a loss of lift, while surveying an area for spraying near Culpeper, Virginia. The certificated commercial pilot was not injured. The aerial application flight was conducted under the provision of 14 Code of Federal Regulations Part 137. Visual meteorological conditions prevailed and no flight plan was filed for the local flight. The flight originated from a nearby open area on the pilot's property about 1215. The pilot reported that he was flying approximately 150 to 200 feet above ground level when he noted an uncommanded high engine rpm; the helicopter turned approximately 60 degrees in heading, and experienced a loss of lift. He reduced the collective and initiated an auto rotation. After the helicopter came to rest, the pilot exited the helicopter, and reported that the transmission was "hot" and the transmission cooler was "the same temperature as the outside air temperature." According to photographs provided by a Federal Aviation Administration (FAA) inspector that responded to the accident location, the helicopter was resting on the hopper that was utilized to carry the applicant and it was leaning about 45 degrees to the left. The tailboom was severed and the main rotor blades were damaged. The pilot, age 55, held a commercial pilot certificate, with ratings for airplane single-engine land, rotorcraft-helicopter, and instrument airplane. The pilot reported to the FAA inspector that he accumulated 12,382 total hours of flight experience and 1,500 hours in the accident helicopter make and model. His most recent FAA second-class medical certificate was issued on October 12, 2010. The helicopter was manufactured in 1982 and was equipped with a Lycoming VO-540-C2A, 315- horsepower engine. At the time of the accident, it was registered with the FAA in the standard-restricted category and used for aerial application. The helicopter's most recent continued airworthiness inspection and engine overhaul was completed on March 18, 2011. At that time, the helicopter had accrued about 3,340.4 total hours of operation and had a Hobbs meter time of 250.6 hours. During the inspection the main rotor transmission was removed to facilitate engine removal and overhaul. The transmission oil was drained, the oil filter was removed and inspected, with "no metal detected." The transmission gear box was reinstalled and serviced with oil as required in the Hiller Maintenance Manual. An engine run and flight test were completed and "all test results [were] within parameters" and "all systems were operating normally." The helicopter had flown 1.8 hours since the last inspection and engine overhaul. ## Aircraft - Registration: [N4033P](https://openairdocs.org/deregistered/N4033P-2013-08-08), registration cancelled 2013-08-08, S/N 5178, built 1982 (OpenAirDocs) - Reported make and model: HILLER UH-12E - Registry model: [Hiller UH-12E](https://openairdocs.org/model/hiller-uh-12e) (registry code 4360122) (OpenAirDocs) - Registry engine: [Lycoming VO-540 series](https://openairdocs.org/engine/lycoming-vo-540-series) (registry code 41582, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 5178 - Airframe hours: 3340 - Engines: LYCOMING VO-540-C2A 315 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Kritter Cropdusting, Inc - Registered owner: Kritter Cropdusting, Inc - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Continuous airworthiness, March 18, 2011, 2 hours before - Departed: Culpeper, VA - Destination: Culpeper, VA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 55; injuries: none; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review October 23, 2009; seat: left; flight hours: 13,000 total, 1,500 in this make and model, 13,000 as pilot in command, 7 in the last 90 days, 7 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 240° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 46 °F, dew point 28 °F - Altimeter: 30.02 inHg - Observed at: CJR, 5 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 20110325004879A](https://openairdocs.org/incident/20110325004879A), Mar 25, 2011: Hiller UH-12E, Culpepper, VA, Substantial damage. Upon arriving at the job site to begin aerial application the pilot noted an uncommanded increase in engine RPM accompanied by a loss of lift. He reduced… ## Other investigations on N4033P (1) 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 NYC84LA212](https://openairdocs.org/ntsb/NYC84LA212), Jun 17, 1984: Hiller 12E (N4033P), Meadville, PA, substantial damage ## Docket (6 files) The files NTSB released with the investigation on July 17, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=78696. 6.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 420 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40359992&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Culpeper Weather (item 2, .PDF, 100 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40346217&FileExtension=.PDF&FileName=Culpeper%20Weather-Master.PDF - Aircraft Maintenace Records [Excerpts] (item 3, .PDF, 491 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40361395&FileExtension=.PDF&FileName=Aircraft%20Maintenace%20Records%20%5BExcerpts%5D-Redacted.PDF - Photo 1: Left Side of Helicopter at Rest (Courtesy of the FAA) (item 4, .PDF, 175 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40359993&FileExtension=.PDF&FileName=Photo%201%3A%20Left%20Side%20of%20Helicopter%20at%20Rest%20(Courtesy%20of%20the%20FAA)-Master.PDF - Photo 2: Right Side of the Helicopter at Rest (Courtesy of the FAA) (item 5, .PDF, 2.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40359994&FileExtension=.PDF&FileName=Photo%202%3A%20Right%20Side%20of%20the%20Helicopter%20at%20Rest%20(Courtesy%20of%20the%20FAA)-Master.PDF - Photo 3: Helicopter Mast and Transmission. (Photo Courtesy of the FAA) (item 6, .PDF, 2.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40359995&FileExtension=.PDF&FileName=Photo%203%3A%20Helicopter%20Mast%20and%20Transmission.%20(Photo%20Courtesy%20of%20the%20FAA)-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.