# NTSB CEN21LA242: Piper J4A, N8501Z, Omaha, NE, May 30, 2021 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: May 30, 2021, 09:55 local (14:55 UTC) - Place: Omaha, NE - Coordinates: 41.369612, -96.022191 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.3696&lon=-96.0222&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Fuel related](https://openairdocs.org/ntsb-events/190) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: Piper Aircraft, FAA Lincoln FSDO - NTSB case key (mKey): 103179 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN21LA242 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/103179/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=103179 - Page: https://openairdocs.org/ntsb/CEN21LA242 ## Probable cause A total loss of engine power due to a blocked fuel tank cap vent hole, which resulted in fuel starvation. Contributing to the accident was the mechanic’s and the pilot’s inadequate inspections of the fuel tank cap. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Fuel system](https://openairdocs.org/ntsb-findings/01022800): Aircraft › Aircraft systems · Incorrect use/operation (probable cause); cases with it: [Piper J4A, 1 case](https://openairdocs.org/ntsb-findings/01022800/cases.md?model=7100604), [All aircraft, 181 cases](https://openairdocs.org/ntsb-findings/01022800/cases.md) - [Fuel system](https://openairdocs.org/ntsb-findings/01022800): Aircraft › Aircraft systems · Damaged/degraded (probable cause); cases with it: [Piper J4A, 1 case](https://openairdocs.org/ntsb-findings/01022800/cases.md?model=7100604), [All aircraft, 181 cases](https://openairdocs.org/ntsb-findings/01022800/cases.md) - [Inspection: preflight inspection](https://openairdocs.org/ntsb-findings/02061510): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Piper J4A, 1 case](https://openairdocs.org/ntsb-findings/02061510/cases.md?model=7100604), [All aircraft, 551 cases](https://openairdocs.org/ntsb-findings/02061510/cases.md) - [Inspection: scheduled/routine inspection](https://openairdocs.org/ntsb-findings/02061520): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Piper J4A, 1 case](https://openairdocs.org/ntsb-findings/02061520/cases.md?model=7100604), [All aircraft, 167 cases](https://openairdocs.org/ntsb-findings/02061520/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Takeoff: Fuel related](https://openairdocs.org/ntsb-events/190) (defining event); cases with it: [Piper J4A, 1 case](https://openairdocs.org/ntsb-events/190/sequence.md?model=7100604), [All aircraft, 361 cases](https://openairdocs.org/ntsb-events/190/sequence.md) - [Takeoff: Fuel starvation](https://openairdocs.org/ntsb-events/191); cases with it: [Piper J4A, 1 case](https://openairdocs.org/ntsb-events/191/sequence.md?model=7100604), [All aircraft, 733 cases](https://openairdocs.org/ntsb-events/191/sequence.md) - [Takeoff: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341); cases with it: [Piper J4A, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=7100604), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Takeoff: Attempted remediation/recovery](https://openairdocs.org/ntsb-events/060); cases with it: [Piper J4A, 1 case](https://openairdocs.org/ntsb-events/060/sequence.md?model=7100604), [All aircraft, 1,422 cases](https://openairdocs.org/ntsb-events/060/sequence.md) - [Landing: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Piper J4A, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=7100604), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing: Collision during takeoff/land](https://openairdocs.org/ntsb-events/490); cases with it: [Piper J4A, 1 case](https://openairdocs.org/ntsb-events/490/sequence.md?model=7100604), [All aircraft, 1,309 cases](https://openairdocs.org/ntsb-events/490/sequence.md) ## Analysis During takeoff, the airplane traveled about three-quarters of the way down the runway and climbed to about 300 ft above ground level. The engine sputtered once and stopped producing power. The pilot switched the fuel selector from the forward fuel tank to the auxiliary fuel tank and unsuccessfully tried to restart the engine. The pilot maneuvered the airplane for a forced landing, and the airplane impacted the ground. The pilot reported that fuel was pouring into the cockpit after the airplane came to rest, and he quickly exited the airplane. The airplane sustained substantial damage to both wings and the fuselage. A postaccident examination revealed that the forward fuel tank cap was not the correct part for the airplane; the cap had an unknown part number etched on it with no manufacturer name displayed. The fuel tank cap appeared to be manufactured with a single vent hole and was equipped with two worn gaskets stacked under the cap. The lower gasket had multiple visible cracks present on both sides of it. The upper gasket was wrinkled and was displaced toward the vent hole, which blocked the venting capability of the fuel tank. For the accident model airplane, the sole source of venting for the forward fuel tank was through a vented fuel tank cap. The pilot reported that the forward fuel tank cap was on the airplane when he purchased it several years ago. The pilot did not have any knowledge of the origin or the background of the forward fuel tank cap. It is likely the engine sustained fuel starvation during the takeoff due to blockage of the forward fuel tank cap vent hole. Based on the available evidence, it could not be determined when the vent hole became blocked. The accident occurred 39 days and 2.3 flight hours after the most recent annual inspection. During the inspection, the mechanic should have observed the multiple visible cracks present on both sides of the lower gasket in the fuel tank cap. Further, during the preflight inspection, the pilot should have observed the multiple visible cracks present on both sides of the lower gasket in the fuel tank cap. Had the deficiencies with the fuel tank cap gasket been observed during the annual inspection or preflight, it is likely the fuel tank cap would have been replaced. ## Factual narrative On May 30, 2021, about 0955 central daylight time, a Piper J4A airplane, N8501Z, sustained substantial damage when it was involved in an accident near Omaha, Nebraska. The pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that during the preflight inspection, he filled the forward (main) fuel tank to about 1 inch below the top and noted that the auxiliary fuel tank contained 4 gallons of fuel. The pilot used a stick to “dip” the two fuel tanks and validate the amount of fuel in them. The pilot planned on departing from North Omaha Airport (3NO), Omaha, Nebraska, for flight operations in the airport’s traffic pattern. Before the takeoff, the fuel selector was positioned for the forward fuel tank. During the takeoff, the airplane traveled about three-quarters of the way down the runway and climbed to about 300 ft above ground level. The engine sputtered once and stopped producing power. The pilot switched the fuel selector to the auxiliary fuel tank and tried to restart the engine unsuccessfully. The pilot maneuvered the airplane for a forced landing, and the airplane impacted the ground and came to rest next to a tree in a field. The pilot reported that fuel was pouring into the cockpit after the airplane came to rest, and he quickly egressed from the cockpit. The airplane sustained substantial damage to both wings and the fuselage. A postaccident examination of the airframe and engine revealed that the fuel tank cap found installed on the filler neck of the forward fuel tank did not appear to be the correct part for the airplane; it had a part number of 2501621 etched on it with no manufacturer name displayed. The fuel tank cap appeared to be manufactured with a single vent hole. The fuel tank cap was equipped with two worn gaskets stacked under the cap. The lower gasket had multiple visible cracks present on both sides of it. The upper gasket was wrinkled and was displaced toward the vent hole, which blocked the venting capability of the fuel tank. Based on the available evidence, it could not be determined when the vent hole became blocked. No fuel was observed in the forward fuel tank, which had sustained impact damage. For the accident model airplane, the sole source of venting for the forward fuel tank is through a vented fuel tank cap. The approved part numbers for the forward fuel tank caps from the original equipment manufacturer (Piper) are A748 (the older style) or 00062-40 (the newer style). The pilot reported that the forward fuel tank cap was on the airplane when he purchased it several years ago. The pilot and his brother purchased the airplane together in March 2011, and the pilot became the sole owner in October 2017. The pilot did not have any knowledge of the origin or the background of the forward fuel tank cap. According to the airplane’s maintenance logbook, during the airplane’s most recent annual inspection, the airplane wasinspected per Piper Inspection Sheets 230-3000. The accident occurred 39 days after the inspection, and 2.3 airplane flight hours had accumulated since the inspection. The inspection sheets listed the inspection criteria, which included: Inspect fuel tank and lines for damage, leaks, water, and seals for deterioration, and cap for venting if applicable. The FAA Airplane Flying Handbook (FAA-H-8083-3B) discusses preflight procedures and states in part: Checking the fuel tank vent is an important part of a preflight assessment. If outside air is unable to enter the tank as fuel is drawn into the engine, the eventual result is fuel starvation and engine failure. During the preflight assessment, the pilot should look for signs of vent damage and blockage. Some airplanes utilize vented fuel caps, fuel vent tubes, or recessed areas under the wings where vents are located. The pilot should use a flashlight to look at the fuel vent to ensure that it is free from damage and clear of obstructions. If there is a rush of air when the fuel tank cap is cracked, there could be a serious problem with the vent system. Aviation Safety, a journal about risk management and aviation accident prevention, published an article on September 23, 2017, titled “Fuel Systems 101.” This article discusses the importance of inspecting fuel tank caps and states: Fuel caps should be checked not only for security but for any deficiencies such as cracked or missing gaskets, plus fuel stains on the wing aft of the fuel filler area indicating corrective action is necessary to resolve poor sealing. Fuel caps be of the vented or non-vented type; always install a fuel cap with the type required for the exact application. ## Aircraft - Registration: [N8501Z](https://openairdocs.org/deregistered/N8501Z-2023-01-14), registration cancelled 2023-01-14, S/N 4-1231, built 1940 (OpenAirDocs) - Reported make and model: PIPER J4A (NO SERIES) - Registry model: [Piper J4A](https://openairdocs.org/model/piper-j4a) (registry code 7100604) (OpenAirDocs) - Registry engine: [Continental C85-12](https://openairdocs.org/engine/continental-c85-12) (registry code 17124, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 4-1231 - Year built: 1940 - Airframe hours: 1653.1 - Engines: CONT MOTOR C85-12F 85 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 14, 2021, 2.3 hours before - Airport: 3NO, North Omaha, runway 17/35, 3,173 × 40 ft, concrete - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 65; injuries: minor; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review February 23, 2020; seat: left; restraint: 3-point; flight hours: 180 total, 35 in this make and model, 91 as pilot in command, 2 in the last 90 days, 2 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Temperature: 55 °F, dew point 48 °F - Altimeter: 30.23 inHg - Observed at: KBTA, 5 nm away - METAR: KBTA 301455Z AUTO 00000KT 10SM -RA BKN070 OVC090 13/09 A3023 RMK AO2 T01300093 ## 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 20210530009419A](https://openairdocs.org/incident/20210530009419A), May 30, 2021: Piper J4A, Omaha, NE, Substantial damage. On may 30, 2021 at approximately 0945 central daylight time, a Piper J4A airplane was substantially damage due to impact with terrain shortly after takeoff at… ## Docket (4 files) The files NTSB released with the investigation on July 27, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=103179. 29.6 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 5.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13232206&FileExtension=pdf&FileName=NTSB%20Form%206120_1%20Redacted-Rel.pdf - Accident photographs (item 2, PDF, 10 pages, 7.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13231051&FileExtension=pdf&FileName=Accident%20Photographs-Rel.pdf - Additional documents (item 3, PDF, 16 pages, 16.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13231410&FileExtension=pdf&FileName=Additional%20Documents%20Redacted-Rel.pdf - NTSB party member form - Piper aircraft (item 4, PDF, 1 page, 52 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13231957&FileExtension=pdf&FileName=NTSB%20Party%20Member%20Form%20-%20Piper%20Aircraft%20Redacted-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.