# NTSB CEN15LA377: Grumman G 164B, N311AL, Sac City, IA, August 12, 2015 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 12, 2015, 16:00 local (21:00 UTC) - Place: Sac City, IA - Coordinates: 42.425834, -94.961669 - Nearby events: https://openairdocs.org/map.md?lat=42.4258&lon=-94.9617&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report March 2, 2016 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA FSDO - NTSB case key (mKey): 91853 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN15LA377 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/91853/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=91853 - Page: https://openairdocs.org/ntsb/CEN15LA377 ## Probable cause The loss of engine power for reasons that could not be determined based on the available information. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined (probable cause); cases with it: [Grumman G-164B, 1 case](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=3952703), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Grumman G-164B, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=3952703), [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 G-164B, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=3952703), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The airline transport pilot reported that he changed the engine oil the night before the accident flight. The next day, he performed a normal engine run-up and then departed on the agricultural application flight. The airplane's tail lifted when the airplane reached 60 mph, and the airplane then accelerated to 80 mph. Shortly after getting airborne, the pilot felt that the airplane was not performing as it should be and that the engine power was decreasing. He advanced the engine controls full forward and selected a cornfield for the forced landing. The pilot reported that he thought that the engine's blower/supercharger had failed because the engine did not stop but did seem to lose power. An engine examination was not performed; therefore, the reason for the loss of engine power could not be determined. ## Factual narrative On August 12, 2015, about 1600 central daylight time, a Grumman G-164B agricultural airplane, N311AL, lost engine power shortly after take-off near Sac City, Iowa. The pilot was not injured and the airplane was substantially damaged during the forced landing. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 137 as an agricultural flight. Visual meteorological conditions prevailed at the time. According to the pilot, he changed the engine oil the night before and completed a 45 minute engine run. On the accident day, he performed a normal run-up and everything appeared normal. He noted a 50 rpm drop per magneto during the engine run-up. He then departed down the runway and lifted the tail at 60 mph and accelerated to 80 mph. Shortly after getting airborne, he felt the airplane was not preforming as it should. The airplane was able to climb over a set of wires, but the engine power faded. He advanced the engine controls full forward, and then selected a cornfield to perform the forced landing in. During the landing, the airplane nosed over and came to rest inverted. Due to the un-harvested corn field, the airplane remained on site until about November 7, so an engine examination was not performed. The pilot added that he thought the engine's blower/supercharger had failed, since the engine didn't stop, but seemed to lose power. A completed NTSB 6120 form was not returned by the operator. ## Aircraft - Registration: [N311AL](https://openairdocs.org/deregistered/N311AL-2020-10-03), registration cancelled 2020-10-03, S/N 255B, built 1977 (OpenAirDocs) - Reported make and model: GRUMMAN G 164B - Registry model: [Grumman G-164B](https://openairdocs.org/model/grumman-g-164b) (registry code 3952703) (OpenAirDocs) - Registry engine: [Pratt & Whitney R-985-AN-1](https://openairdocs.org/engine/pratt-whitney-r-985-an-1) (registry code 51659, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 255B - Year built: 1977 - Engines: P&W 985 reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Airworthiness certificate: Special, Restricted (Special) - Departed: KSKI, Sac City Mun, IA - Destination: KSKI, Sac City Mun, IA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 50; injuries: none; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2; seat: single ## Weather - Conditions: Visual (VMC), Day - Wind: 240° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 82 °F, dew point 66 °F - Altimeter: 30.18 inHg - Observed at: KSLB, 15 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 20150812015879A](https://openairdocs.org/incident/20150812015879A), Aug 12, 2015: Grumman G-164B, Sac City, IA, Destroyed. According to the pilot, he took off from kski and during the climb the aircraft performance deteriorated at approximately 150 AGL. The instruments were reading… ## Docket (2 files) The files NTSB released with the investigation on January 28, 2016, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=91853. 115 KB in all. - Memo (item 1, .PDF, 76 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40436168&FileExtension=.PDF&FileName=Memo-Master.PDF - Weather Reports and Records (item 2, .PDF, 39 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40436169&FileExtension=.PDF&FileName=Weather%20Reports%20and%20Records-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.