# NTSB WPR10LA122: Grumman Acft ENG Cor-Schweizer G-164B, N6799K, Pullman, WA, January 30, 2010

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: January 30, 2010, 10:30 local (18:30 UTC)
- Place: Pullman, WA
- Coordinates: 46.740554, -117.103332 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=46.7406&lon=-117.1033&mi=10
- Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping)
- Defining event: [Takeoff: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report May 28, 2010
- Report: Approved by Office Director
- NTSB office: Western Pacific Region
- Parties: Spokane FSDO
- NTSB case key (mKey): 75320
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR10LA122
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/75320/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=75320
- Page: https://openairdocs.org/ntsb/WPR10LA122

## Probable cause

A partial loss of engine power during takeoff due to a bird's nest being sucked into the induction air ducting.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Power plant: air intake](https://openairdocs.org/ntsb-findings/01057160): Aircraft › Aircraft power plant · Damaged/degraded (probable cause); cases with it: [Grumman Acft ENG Cor-Schweizer G-164B, 1 case](https://openairdocs.org/ntsb-findings/01057160/cases.md?model=3952802), [All aircraft, 50 cases](https://openairdocs.org/ntsb-findings/01057160/cases.md)
- [Terrain: rough terrain](https://openairdocs.org/ntsb-findings/03021015): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Grumman Acft ENG Cor-Schweizer G-164B, 2 cases](https://openairdocs.org/ntsb-findings/03021015/cases.md?model=3952802), [All aircraft, 442 cases](https://openairdocs.org/ntsb-findings/03021015/cases.md)
- [Object/animal/substance: debris/dirt/foreign object](https://openairdocs.org/ntsb-findings/03022055): Environmental issues › Physical environment · Effect on equipment (probable cause); cases with it: [Grumman Acft ENG Cor-Schweizer G-164B, 1 case](https://openairdocs.org/ntsb-findings/03022055/cases.md?model=3952802), [All aircraft, 101 cases](https://openairdocs.org/ntsb-findings/03022055/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Takeoff: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Grumman Acft ENG Cor-Schweizer G-164B, 8 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=3952802), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md)
- [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Grumman Acft ENG Cor-Schweizer G-164B, 17 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=3952802), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md)
- [Landing-landing roll: Nose over/nose down](https://openairdocs.org/ntsb-events/096); cases with it: [Grumman Acft ENG Cor-Schweizer G-164B, 19 cases](https://openairdocs.org/ntsb-events/096/sequence.md?model=3952802), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md)

## Analysis

Due to the cold temperatures on the morning of the flight, the pilot followed the “Cold Weather Engine Operation” procedures in the Ag-Cat pilot handbook. Because those procedures called for the engine oil and cylinder head temperatures to reach a minimum level before takeoff, the pilot had run the engine on the ground for about 30 minutes prior to performing the pre-takeoff run-up check. During that check he exercised the carburetor heat system, which worked as prescribed. During the long run-up, a bird’s nest became dislodged and was sucked into the area near the carburetor inlet screen during the carburetor heat test. The condition of the nest remains indicated that during the increased volume and velocity air flow during takeoff, the nest partially disintegrated and ultimately covered a significant portion of the inlet screen surface. According to the Federal Aviation Administration inspector who monitored the engine inspection, the nest was located inside the warm air pick-up ducting, which is an area that the pilot would not normally see into or check unless there was external visual evidence to indicate the need for a further inspection.

## Factual narrative

On January 30, 2010, about 1030 Pacific standard time, a Grumman G-164B, N6799K, nosed over in an open field during a forced landing about one minute after taking off from Pullman-Moscow Regional Airport, Pullman, Washington. The commercial pilot was not injured, but the airplane, which had just been purchased by Pleasant Valley Aviation, American Falls, Idaho, was substantially damaged. The local pre-ferry familiarization flight was being conducted under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed in the area of the accident. No flight plan had been filed. According to the pilot, just about the time he passed the end of the runway at about 150 feet above ground level (agl), the airplane's engine began to lose power. Because he did not have enough power to keep the airplane airborne, the pilot maneuvered to land in an open field of freshly planted winter wheat. Although the touchdown was successful, during the landing roll on the soft rough terrain, the main landing gear wheels began to sink into the dirt, and the airplane nosed over onto its top wing. During the nose-over sequence the airplane's wing structure was substantially damaged. During a post-accident inspection of the airframe and engine, it was discovered that a bird's nest had been sucked from the carburetor heat warm air pickup ducting, upstream from the carburetor heat valve, and lodged in the carburetor intake screen, cutting off a significant portion of the induction air flow. Further discussions with the pilot determined that due to the cold temperatures on the morning of the flight, he followed the “Cold Weather Engine Operation” procedures in the Ag-Cat pilot handbook. Because those procedures called for the engine oil and cylinder head temperatures to reach a minimum level before takeoff, the pilot had run the engine on the ground for about 30 minutes prior to performing the pre-takeoff run-up check. During that check he exercised the carburetor heat system, which worked as prescribed. It is thus surmised that during the long run-up, the bird’s nest became dislodged and was sucked into the area near the carburetor inlet screen during the carburetor heat test. The condition of the nest remains indicated that during the increased volume and velocity air flow during takeoff, the nest partially disintegrated and ultimately covered a significant portion of the inlet screen surface (see docket photo). According to the Federal Aviation Administration (FAA) Inspector who monitored the airframe and engine inspection, the nest was located up inside the warm air pick up ducting, which is an area that the pilot would not normally see up into or check unless there was external visual evidence to indicate the need for a further inspection.

## Aircraft

- Registration: [N6799K](https://openairdocs.org/deregistered/N6799K-2013-11-12), registration cancelled 2013-11-12, S/N 493 B, built 1979 (OpenAirDocs)
- Reported make and model: GRUMMAN ACFT ENG COR-SCHWEIZER G-164B
- Registry model: [Grumman Acft ENG Cor-Schweizer G-164B](https://openairdocs.org/model/grumman-acft-eng-cor-schweizer-g-164b) (registry code 3952802) (OpenAirDocs)
- Registry engine: [Pratt & Whitney R-1340-AN-1](https://openairdocs.org/engine/pratt-whitney-r-1340-an-1) (registry code 51612, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 493 B
- Airframe hours: 10712
- Engines: P & W R-1340-AN-1 600 horsepower reciprocating
- Damage: Substantial damage
- Flight: Ferry, Part 91
- Operator: Pleasant Valley Aviation
- Registered owner: Pleasant Valley Aviation
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, October 30, 2008
- Departed: KPUW, Pullman, WA
- Destination: KPUW, Pullman, WA
- Airport: KPUW, Pullman-Moscow Regional

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 41; injuries: none; flight instructor, commercial; airplane ratings: multi-engine land, single-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review February 4, 2009; seat: front; flight hours: 1,700 total, 52 in this make and model, 1,600 as pilot in command, 5 in the last 90 days, 0 in the last 30 days, 0 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 10 statute miles
- Lowest ceiling: 12,000 ft broken
- Temperature: 41 °F, dew point 30 °F

## 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 20100130026489A](https://openairdocs.org/incident/20100130026489A), Jan 30, 2010: Grumman Acf G-164B, Pullman, WA, Substantial damage. Pilot departed runway 23 Pullman airport, Pullman, WA on a ferry permit for a flight to American falls, ID. At approximately 150 feet AGL the aircraft started…

## Docket (3 files)

The files NTSB released with the investigation on March 31, 2010, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=75320. 1.8 MB in all.

- Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40326962&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF
- FAA Statement (item 2, .PDF, 17 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40326963&FileExtension=.PDF&FileName=FAA%20Statement-Redacted.PDF
- Image 1. Remnants of bird's nest. (item 3, .PDF, 54 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40326964&FileExtension=.PDF&FileName=Image%201.%20Remnants%20of%20bird%27s%20nest.-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.

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