# NTSB ERA24LA286: Grumman G-164A, N7849, Toccoa, GA, June 29, 2024 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: June 29, 2024, 18:40 local (22:40 UTC) - Place: Toccoa, GA - Coordinates: 34.592812, -83.296372 - Nearby events: https://openairdocs.org/map.md?lat=34.5928&lon=-83.2964&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Loss of control on ground](https://openairdocs.org/ntsb-events/230) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Eastern Region Aviation - Parties: Honeywell, FAA/FSDO - NTSB case key (mKey): 194586 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA24LA286 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/194586/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=194586 - Page: https://openairdocs.org/ntsb/ERA24LA286 ## Probable cause The pilot’s failure to set the engine speed control fully forward during takeoff, resulting in an engine surge and subsequent loss of control during landing. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters: powerplant parameters](https://openairdocs.org/ntsb-findings/01062050): Aircraft › Aircraft oper/perf/capability · Incorrect use/operation (probable cause); cases with it: [Grumman G-164A, 1 case](https://openairdocs.org/ntsb-findings/01062050/cases.md?model=3952704), [All aircraft, 81 cases](https://openairdocs.org/ntsb-findings/01062050/cases.md) - [Action: incorrect action performance](https://openairdocs.org/ntsb-findings/02041015): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Grumman G-164A, 1 case](https://openairdocs.org/ntsb-findings/02041015/cases.md?model=3952704), [All aircraft, 1,386 cases](https://openairdocs.org/ntsb-findings/02041015/cases.md) - [Performance/control parameters: directional control](https://openairdocs.org/ntsb-findings/01062020): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Grumman G-164A, 3 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md?model=3952704), [All aircraft, 3,958 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-climb to cruise: Miscellaneous/other](https://openairdocs.org/ntsb-events/900); cases with it: [Grumman G-164A, 1 case](https://openairdocs.org/ntsb-events/900/sequence.md?model=3952704), [All aircraft, 1,556 cases](https://openairdocs.org/ntsb-events/900/sequence.md) - [Landing-landing roll: Loss of control on ground](https://openairdocs.org/ntsb-events/230) (defining event); cases with it: [Grumman G-164A, 2 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=3952704), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) ## Analysis The pilot of the turbo propeller-powered agricultural airplane reported that, during takeoff for a cross-county flight, the engine rpm did not reach 100% but he continued the flight. Shortly after takeoff, the engine appeared to surge and the pilot decided to return to the departure airport. As he approached the airport, the surging worsened and, after touchdown, the engine power started to increase. He tried to shut down the engine, but the power continued to increase. He applied heavy braking to slow the airplane; the left brake then locked, and the airplane departed the runway and the airplane’s wings were substantially damaged. Postaccident examination of the engine revealed damage indicative of an engine that was rotating and operating at the time of impact; no pre-existing condition was found that would have prevented normal engine operation or control. The engine manufacturer issued a Pilot Advisory Letter more than 10 years before the accident addressing the issue of engine oscillations. The letter noted: When performing a takeoff, pilots normally advance the power lever(s) to a takeoff value as specified in the POH/AFM and as indicated on the torque (or equivalent) gauge. If a takeoff is attempted with the Engine Speed Control(s) in any position other than full forward, resulting in the engine not achieving 100-101% RPM, the engine(s) may very well achieve the desired indicated torque; however, the engine(s) will actually develop a reduced level of horsepower. A reduced level of horsepower will result in the degradation of aircraft performance. The letter added that, “One and possibly two adverse effects can result if a takeoff is attempted with the Engine Speed Control(s) in any position other than full forward. They are reduced power output from the engine(s) and the possibility of accompanying engine oscillations.” Since the previous 22 hours of flying did not demonstrate this type of engine behavior, postaccident examination of the engine found no issues that would have prevented normal operation, and the pilot reported both not achieving 100% speed as well as engine oscillations during and after takeoff, the pilot likely did not advance the engine speed control fully forward during takeoff. ## Factual narrative On June 29, 2024, about 1840 eastern daylight time, a Grumman G-164A, N7849, was substantially damaged when it was involved in an accident near Toccoa, Georgia. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 positioning flight. According to the pilot, he departed Toccoa Airport-RG Letourneau Field (TOC), Toccoa, Georgia, for Walnut Ridge Regional Airport (ARG), Walnut Ridge, Arkansas. During takeoff, he noticed the engine rpm did not reach 100% but he continued the flight. Shortly after takeoff, the engine appeared to surge and the pilot decided to return to the departure airport. As he approached the airport, the engine surging worsened. During touchdown, he pulled the throttle back to beta; however, the engine started to increase in power. He tried to shut down the engine, but it continued to increase in power. He applied heavy braking to slow the airplane down; the left brake then locked, and the airplane departed the left side of the runway. The right main landing gear separated and the wings were substantially damaged. Postaccident examination of the engine revealed that the engine’s main shaft, torsion shaft, first-stage compressor impeller shroud, first-stage impeller, first-stage diffuser, second-stage compressor housing, and second-stage compressor impeller, displayed rotational scoring and damage that was consistent with an engine that was rotating and operating at the time of impact. The aft turbine bearing support assembly was submitted to the manufacturer’s failure analysis group for further analysis. According to the manufacturer’s report, the separation of one strut and cracking of the inner and outer portions of the other struts resulted from overload. No evidence of fatigue was observed on the fractured struts. The strut base material was verified by energy-dispersive Xray and microstructural analysis to be the specified IN713C nickel alloy in the cast condition. No material anomalies were observed, and no pre-existing condition was found that would have prevented normal operation. The manufacturer issued Pilot Advisory Letter (PAL) PA331-09 in August 2013, addressing the issue of engine oscillations. The PAL read in part: When performing a takeoff, pilots normally advance the power lever(s) to a takeoff value as specified in the POH/AFM and as indicated on the torque (or equivalent) gauge. If a takeoff is attempted with the Engine Speed Control(s) in any position other than full forward, resulting in the engine not achieving 100-101% RPM, the engine(s) may very well achieve the desired indicated torque; however, the engine(s) will actually develop a reduced level of horsepower. A reduced level of horsepower will result in the degradation of aircraft performance. The letter also notes that, “One and possibly two adverse effects can result if a takeoff is attempted with the Engine Speed Control(s) in any position other than full forward. They are reduced power output fromthe engine(s) and the possibility of accompanying engine oscillations…The primary driving function for these oscillations is that the fuel control’s Main Metering Valve (MMV) set point has intersected the acceleration schedule.” Review of the accident airplane’s maintenance logbook revealed that the engine was installed on November 15, 2023. At the time of the accident, it had accumulated 22 hours of operation. ## Aircraft - Registration: [N7849](https://openairdocs.org/aircraft/N7849), registered now, S/N 797 (OpenAirDocs) - Reported make and model: GRUMMAN G-164A - Registry model: [Grumman G-164A](https://openairdocs.org/model/grumman-g-164a) (registry code 3952704) (OpenAirDocs) - Registry engine: [Pratt & Whitney R1340 series](https://openairdocs.org/engine/pratt-whitney-r1340-series) (registry code 52016, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 797 - Year built: 1971 - Airframe hours: 12212.1 - Engines: Honeywell TPE 331-1-151A 600 horsepower reciprocating - Damage: Substantial damage - Flight: Positioning, Part 91 - Airworthiness certificate: Special, Restricted (Special) - Last inspection: 100 hour, May 1, 2024 - Destination: ARG, Walnut Ridge, AR - Airport: TOC, Toccoa Airport-RG Letourneau Field, runway 21, 5,008 × 100 ft, asphalt - Equipment: Handheld GPS ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 33; injuries: none; commercial; airplane ratings: single-engine land; medical: class 2, without waivers/limitations; seat: single; restraint: 4-point; flight hours: 1,001 total ## Weather - Conditions: Visual (VMC), Day - Wind: 90° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: 3,900 ft broken - Temperature: 90 °F, dew point 73 °F - Altimeter: 30.08 inHg - Observed at: TOC - METAR: KTOC 292235Z AUTO 09004KT 10SM BKN039 BKN050 32/23 A3008 RMK AO2 T03250227 ## 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 20240629015779A](https://openairdocs.org/incident/20240629015779A), Jun 29, 2024: Grumman G-164A, Toccoa, GA, Substantial damage. Upon landing rollout, the aircraft veered off the left side of runway. The right landing gear collapsed, and the right wing and propeller struck the ground. ## Other investigations on N7849 (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 FTW79DPG24](https://openairdocs.org/ntsb/FTW79DPG24), Mar 28, 1979: Grumman G-164A (N7849), Vilonia, AR, substantial damage ## Docket (10 files) The files NTSB released with the investigation on September 11, 2025, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=194586. 55.5 MB in all. - Memorandum for record - 6120.1 pilot/operator report form (item 1, PDF, 1 page, 108 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18830604&FileExtension=pdf&FileName=MEMORANDUM%20FOR%20RECORD-email%20about%206120-Rel.pdf - Memorandum for record a�� telephone interview, pilot (item 2, PDF, 1 page, 134 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19164575&FileExtension=pdf&FileName=Memo%20for%20record-pilot%20interview-Rel.pdf - Maintenance records (item 3, PDF, 5 pages, 5.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18828584&FileExtension=pdf&FileName=Maintenance%20logbooks_Redacted-Rel.pdf - Honeywell pilot advisory letter (item 4, PDF, 2 pages, 23 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19010834&FileExtension=pdf&FileName=PAL331-09-Rel.pdf - Honeywell teardown report (item 5, PDF, 177 pages, 43.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19222405&FileExtension=pdf&FileName=TPE331-1-151A%20Teardown%20Report%20(P-91125C)-Rel.pdf - Honeywell metallurgy report (item 6, PDF, 14 pages, 4.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19222415&FileExtension=pdf&FileName=ERS-ASYS-PENG-MA-0001006-A%20(NTSB)-Rel.pdf - Investigative photographs (item 7, PDF, 3 pages, 898 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18831376&FileExtension=pdf&FileName=Investigative%20Photos-Rel.pdf - Wreckage examination summary (item 8, PDF, 5 pages, 203 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18830594&FileExtension=pdf&FileName=Wreckage%20Examination%20Summary-Rel.pdf - Statement of party representatives to NTSB investigation (item 9, PDF, 1 page, 240 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19010328&FileExtension=pdf&FileName=Party-Representative%20(Eller)_Redacted-Rel.pdf - Evidence control form (item 10, PDF, 1 page, 114 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19023584&FileExtension=pdf&FileName=Evidence-Control-Form-Rel.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.