# NTSB SEA99LA107: Grumman-Schweizer G-164A, N7869, New Plymouth, ID, July 7, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 6, 1999, 19:30 local (Jul 7, 1999, 01:30 UTC) - Place: New Plymouth, ID - Coordinates: 43.940578, -116.799644 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=43.9406&lon=-116.7996&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report January 18, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 46732 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA99LA107 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46732/pdf - Page: https://openairdocs.org/ntsb/SEA99LA107 ## Probable cause Loss of engine power due to failure of the supercharger impeller. A contributing factor was the ditch. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - mech failure/malf, maneuvering - eng assembly,blower/impeller/integral supercharger - failure,partial (cause) - Forced landing, emergency descent/landing - On ground/water encounter with terrain/water, landing - roll - terrain condition - ditch (contributing factor) ## Analysis Immediately after takeoff the pilot sensed a loss of engine performance and attempted to return to the departure airstrip. Unable to maintain altitude, he dumped the chemical load and then initiated a forced landing to an agricultural (sugar beet) field. The pilot was unable to stop the aircraft before reaching an irrigation ditch and impacted the upsloping terrain at the ditch's opposite side. Partial disassembly of the engine revealed that a gear tooth from the engine's supercharger blower section had broken off and was found in the blower drive section. ## Factual narrative On July 6, 1999, approximately 1930 hours mountain daylight time, a Grumman-Schweizer G-164A "AgCat," N7869, registered to Donald Taylor, being operated by Taylor Aviation, and being flown by a commercial pilot, was substantially damaged when the aircraft collided with terrain during the landing roll following a power loss while maneuvering on an aerial application flight one mile north of New Plymouth, Idaho (refer to CHART I). The pilot was uninjured. Visual meteorological conditions existed and no flight plan had been filed. The flight, which was being conducted for the purpose of insecticide/fungicide dispensation over an onion field, was to have been operated under 14CFR137, and originated from a landing strip approximately one mile north of spray site. An inspector from the Federal Aviation Administration's Boise Flight Standards District Office reported that the pilot departed with 140 gallons of insecticide. Immediately after takeoff the pilot sensed a loss of engine performance and attempted to return to the departure airstrip. Unable to maintain altitude, he dumped the chemical load and then initiated a forced landing to an agricultural (sugar beet) field. The pilot was unable to stop the aircraft before reaching an irrigation ditch and impacted the upsloping terrain at the ditch's opposite side (refer to photograph 1). The temperature at the crash site at the time of the accident was estimated to be 90 degrees Fahrenheit. The operator was contacted twice requesting the completion of NTSB Form 6120.1/2 (Pilot/Operator Aircraft Accident Report) but failed to provide the required documentation (refer to ATTACHMENT L-I). A partial engine disassembly was conducted under the oversight of an inspector from the Federal Aviation Administration's Boise Flight Standards District Office. The inspector reported the following: "The supercharger and accessory section was removed as a unit from the back of the engine. Upon removal, a gear tooth was found in the blower drive section. Further investigation found the tooth to be from [the] impeller shaft P/N 6514." No other pre-impact failure or malfunction was noted during the disassembly (refer to ATTACHMENT FAA-I). ## Aircraft - Registration: [N7869](https://openairdocs.org/deregistered/N7869-2006-08-10), registration cancelled 2006-08-10, S/N 1003, built 1972 (OpenAirDocs) - Reported make and model: Grumman-Schweizer G-164A - Registry model: [Grumman Acft ENG Cor-Schweizer G-164A](https://openairdocs.org/model/grumman-acft-eng-cor-schweizer-g-164a) (registry code 3952801) (OpenAirDocs) - Category: Airplane - Serial number: 1003 - Airframe hours: 6227 - Engines: P&W R-985-14B 450 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Taylor, Donald, L. - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, May 3, 1999, 45 hours before ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 62; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: front; flight hours: 14,000 total, 4,000 in this make and model, 2 in the last 90 days ## Weather - Conditions: Visual (VMC), Day - Wind: 350° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 90 °F, dew point 46 °F - Altimeter: 29.00 inHg - Observed at: ONO, 9 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 19990706008419A](https://openairdocs.org/incident/19990706008419A), Jul 6, 1999: Scwzer G164A, New Plymouth, ID, Substantial damage. (-23)Aircraft departed a private spraying airstrip north of New Plymouth, Idaho to spray an onion field adjacent to the strip. After making one spray pass over… ## Other investigations on N7869 (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 FTW73FRA38](https://openairdocs.org/ntsb/FTW73FRA38), Jun 19, 1973: Grumman G-164A (N7869), Bay City, TX, substantial damage 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.