# NTSB ERA24LA016: Cessna 172L, N7716G, Richmond, VA, October 21, 2023 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: October 21, 2023, 13:40 local (17:40 UTC) - Place: Richmond, VA - Coordinates: 37.708944, -77.436639 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=37.7089&lon=-77.4366&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO - NTSB case key (mKey): 193283 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA24LA016 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/193283/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=193283 - Page: https://openairdocs.org/ntsb/ERA24LA016 ## Probable cause The loss of engine power due to a restriction of fuel flow as a result of a fractured float bracket in the carburetor. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine fuel and control: fuel control/carburetor](https://openairdocs.org/ntsb-findings/01057322): Aircraft › Aircraft power plant · Fatigue/wear/corrosion (probable cause); cases with it: [Cessna 172L, 2 cases](https://openairdocs.org/ntsb-findings/01057322/cases.md?model=2072432), [All aircraft, 195 cases](https://openairdocs.org/ntsb-findings/01057322/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-cruise: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) (defining event); cases with it: [Cessna 172L, 2 cases](https://openairdocs.org/ntsb-events/340/sequence.md?model=2072432), [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md) - [Enroute-cruise: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342); cases with it: [Cessna 172L, 5 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=2072432), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Emergency descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Cessna 172L, 21 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=2072432), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The flight instructor reported that the flight was intended to review maneuvers. On the return to their home airport, the engine lost power. The instructor performed an emergency landing in a field where the airplane’s right wing sustained substantial damage when it struck a tree. The postaccident examination of the engine revealed that a float bracket within the carburetor fractured due to cyclic fatigue. This failure would have resulted in a restriction of fuel flow, and the loss of engine power described by the flight instructor. The fracture originated at the bracket’s interior edge with no other anomalies noted. ## Factual narrative On October 21, 2023, at approximately 1340 EDT, a Cessna 172L, N7716G, was substantially damaged when it was involved in an accident near Richmond, Virginia. The flight instructor, student pilot, and one passenger were not injured. The airplane was operating as a Title 14 Code of Federal Regulations Part 91 instructional flight. The flight instructor reported that the purpose of the flight was to conduct a review of flight maneuvers in a designated practice area. On the return flight to OFP, the engine began to lose power. The power loss progressed until the airplane could no longer maintain level flight. The flight instructor initiated an emergency landing in an open field short of the runway. During the landing rollout the right wing struck a tree, resulting in substantial damage. A Federal Aviation Administration inspector conducted an on-site examination and noted that the right wing exhibited damage consistent with impact with a small tree located at the accident site. The cabin section showed damage at the right-wing root attachment area. The left wing displayed upward bending from the wingtip about 2 feet inboard. An engine examination established valvetrain continuity with crankshaft rotation through 720°. Ignition continuity was confirmed during the examination of the magnetos, ignition wires, and spark plugs. An undetermined amount of fuel sufficient for flight was found in both fuel tanks. The carburetor was partially disassembled. It was observed that the float bracket had fractured into two pieces. The float remained attached to the bracket by the float lever shaft, and the float valve was coupled to the float by a clip mounted on the float lever shaft. The float’s movement along the shaft allowed axial motion of the float valve within the float valve seat, restricting fuel flow into the bowl when the valve sealed against the seat. The carburetor components were submitted to the National Transportation Safety Board (NTSB) Materials Laboratory for further examination. Analysis revealed that one arm of the float bracket had fractured due to cyclic fatigue. The fracture surface was flat with radiating lines and curved crack growth features consistent with fatigue failure. The origin of the fracture was along the interior edge where the bracket arm intersected the base of the bracket. No anomalies were observed at the fracture origin. A review of the logbook excerpts revealed that in 2005 there was an IRAN (Inspect & Repair As Necessary) performed that referred to the replacement of the various original accessories including the carburetor. No other maintenance was noted on carburetor since 2005. ## Aircraft - Registration: [N7716G](https://openairdocs.org/aircraft/N7716G), registered now, S/N 17259416, built 1971 (OpenAirDocs) - Reported make and model: CESSNA 172L - Registry model: [Cessna 172L](https://openairdocs.org/model/cessna-172l) (registry code 2072432) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 17259416 - Year built: 1971 - Airframe hours: 4777 - Engines: Lycoming O-360-A4M 180 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, September 6, 2023 - Destination: Same as departure - Airport: OFP, Hanover County Municipal Airport - Equipment: ADS-B, Electronic primary flight display ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 30; injuries: none; flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1; last flight review January 27, 2023; seat: right; restraint: 3-point; flight hours: 600 total, 600 in this make and model, 580 as pilot in command, 200 in the last 90 days, 70 in the last 30 days, 2 in the last 24 hours - Student pilot; injuries: none; student; medical: unknown, unknown; seat: left; restraint: 3-point; flight hours: 2 total, 2 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 180° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point 57 °F - Altimeter: 30.23 inHg - Observed at: KOFP - METAR: METAR KOFP 261954Z AUTO 18008KT 10SM CLR 27/14 A3023 RMK AO2 SLP236 T02670139 ## 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 20231021015249A](https://openairdocs.org/incident/20231021015249A), Oct 21, 2023: Cessna 172L, Hanover, VA, Substantial damage. CFI and student departed airport (Hanover county, VA kofp) traffic pattern and flew to local practice area, performed several private pilot maneuvers at 3000… ## Docket (5 files) The files NTSB released with the investigation on December 5, 2024, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=193283. 11.8 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 7.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17984710&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf - Memorandum for record - wreckage examination summary, FAA (item 2, PDF, 1 page, 66 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17605707&FileExtension=pdf&FileName=FAA%20MOR%20LA016-Rel.pdf - Maintenance records excerpts (item 3, PDF, 3 pages, 973 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17605536&FileExtension=pdf&FileName=Logbook%20excerpt%201_Redacted-Rel.pdf - Materials laboratory factual report 24-040 (item 4, PDF, 12 pages, 13 photos, 2.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17350695&FileExtension=pdf&FileName=Materials%20Laboratory%20Factual%20Report%2024-040-Rel.pdf - Investigation photographs (item 5, PDF, 2 pages, 477 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17649360&FileExtension=pdf&FileName=Investigative%20Photos%20LA016-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.