# NTSB SEA99LA089: Weatherly 620B, N2033N, Tetonia, ID, June 21, 1999 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: June 21, 1999, 07:15 local (13:15 UTC) - Place: Tetonia, ID - Coordinates: 43.850681, -111.109275 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=43.8507&lon=-111.1093&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report November 30, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 46649 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA99LA089 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46649/pdf - Page: https://openairdocs.org/ntsb/SEA99LA089 ## Probable cause A failure of the right magneto drive gear shaft. Factors include the absence of any suitable terrain on which to perform an emergency landing, and the rough/uneven condition of the terrain on which the pilot was forced to land. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, cruise - ignition system,magneto - sheared (cause) - In flight collision with terrain/water, emergency landing - terrain condition - none suitable (contributing factor) - Gear collapsed, landing - roll - terrain condition - rough/uneven (contributing factor) ## Analysis Just after leveling off at 200 feet AGL, the aircraft experienced a significant partial loss of engine power. Because, according to the pilot, the aircraft was not able to stay airborne, he attempted an emergency landing in rough/uneven terrain. During the landing, the right wing caught the terrain and the aircraft was spun around. During this sequence of events, the aircraft's main gear collapsed. The investigation determined that the right magneto gear drive shaft had sheared. No evidence of any other malfunction or anomaly was found. ## Factual narrative On June 21, 1999, approximately 0715 mountain daylight time, a Weatherly 620B, N2033N, collided with the terrain during an emergency landing following a partial loss of engine power near Tetonia, Idaho. The commercial pilot received minor injuries, and the aircraft, which was owned and operated by the pilot, sustained substantial damage. The CFR Part 91 position flight from an agricultural application landing site to the company airstrip was being conducted in visual meteorological conditions. The flight had been airborne for about one minute at the time of the occurrence. No flight plan had been filed, and there was no report of an ELT activation. According to the pilot, who failed to return the Form 6120.1/2, just after he leveled off about 200 feet above the ground, it seemed as if the engine lost all power without any previous sign of impending malfunction. Because there was no suitable open field in which to land, the pilot attempted an emergency landing in a nearby ravine. During the touchdown, the right wing came in contact with the rough/uneven terrain and spun the aircraft around. During this sequence of events, the main landing gear collapsed and the aircraft sustained substantial damage. During the investigation, the aircraft's fuel system, electrical system, air induction system, and ignition system were inspected. No anomalies or contaminants were found in those systems, and both the electrical and mechanical fuel pumps were found to function properly. The NAR9B carburetor was taken to Precision Airmotive Corporation for an operational check and teardown inspection, and no anomalies, internal damage, or contamination were found. In addition, the engine was subjected to a partial teardown inspection, during which it was discovered that the right magneto drive gear shaft had sheared through its most-forward oil supply orifice. Except for the sheared shaft, no other evidence of malfunction or anomalies that would have precluded normal engine operation were found. ## Aircraft - Registration: [N2033N](https://openairdocs.org/deregistered/N2033N-2008-06-17), registration cancelled 2008-06-17, S/N 1584 (OpenAirDocs) - Reported make and model: Weatherly 620B - Registry model: [Weatherly 620B](https://openairdocs.org/model/weatherly-620b) (registry code 9630605) (OpenAirDocs) - Category: Airplane - Serial number: 1584 - Airframe hours: 800 - Engines: P&W R-985- AN1 450 horsepower reciprocating - Damage: Substantial damage - Flight: Positioning, Part 91 - Registered owner: Owen J. Neeley - Airworthiness certificate: Special, Restricted (Special) - Last inspection: 100 hour, June 8, 1999 - Destination: NEWDALE, ID ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 59; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: center; flight hours: 15,000 total ## Weather - Conditions: Visual (VMC), Day - Wind: variable at 10 knots - Visibility: 10 statute miles - Lowest ceiling: none ## 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 19990621007459A](https://openairdocs.org/incident/19990621007459A), Jun 21, 1999: Wthrly 620B, Tetonia, ID, Substantial damage. Acft crashed while transitioning from the aerial application field to the company airstrip, other circumstances are unknown. (From .19) on June 21, 1999,… 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.