NTSB CAROL · Event
Event WPR20LA180
Aircraft involved
Probable cause & findings
Maintenance personnel’s inadequate post-maintenance inspections that resulted in the total loss of engine power due to a blockage in the air intake.
Factual narrative
On June 12, 2020, about 1000 Pacific daylight time, a Bellanca 7KCAB Citabria airplane, N36339, was substantially damaged when it was involved in an accident near Renton, Washington. The certified flight instructor (CFI) and pilot receiving instruction sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The airplane had recently undergone an annual inspection and the accident flight was the first flight since being out of maintenance. The operator, Boeing Employees Flying Association, required that a test flight be performed following annual inspections and the CFI was authorized to perform those flights. The CFI elected to take the pilot receiving instruction for the test flight since she was working on obtaining her tailwheel endorsement. The test flight protocol provided an extended checklist including an elongated preflight and runup. The CFI added 10 gallons of fuel in each wing tank and the engine start and runup were all normal. With the pilot receiving instruction positioned in the front seat, she performed the initial takeoff from runway 16 and they remained in the traffic pattern with the intention of performing touch-and-go takeoff practice and landings. After making an uneventful three-point landing, the pilot receiving instruction applied full throttle and the airplane accelerated reaching an altitude of about 400 feet above ground level (agl). At that time, the engine abruptly stopped producing (total) power, although the propeller continued to rotate. The CFI opted to land on an access road. During the off-airport landing, the airplane sustained substantial damage to both wings and the fuselage when it collided with a tree before coming to rest in a vacant construction company storage area. The CFI stated that the airplane was too low for him to look at the instruments or perform troubleshooting steps and from the rear seat he did not have good visual access to the engine gauges. The pilot receiving instruction stated that immediately following the power loss, the CFI asked her what was happening. She confirmed that the throttle was fully forward, the mixture was rich, and the fuel selector valve and boost pump were both in the ON position. During a postaccident examination, investigators discovered the air induction box contained an approximate two by three feet piece of bunched up paper that was white and had a plastic type coating. The paper appeared to have mostly restricted the inlet cavity (see figure 1). Figure 1: Picture of Air Induction The lead mechanic who performed the annual inspection before the accident stated that as part of the annual inspection, the airplane needed a repair concerning a hole near the exhaust on the lower cowling. He hired a local repair person he normally uses to complete the fiberglass work and painting. After the maintenance, the airplane sat for a day with the lower cowling/ air filter off. After the work was completed and the lower cowling was reinstalled, the mechanic completed a final inspection followed by a post-inspection run-up, with no discrepancies noted. The were no other anomalies found during the postaccident examination. The airplane had recently undergone an annual inspection, and the accident flight was the first flight since being out of maintenance. After making a normal departure and touch-and-go landing, the pilot receiving instruction applied full power. As the airplane reached an altitude of about 400 feet above ground level (agl), the engine abruptly stopped producing (total) power. The airplane could not maintain level altitude and during the subsequent off-airport landing, the airplane was substantially damaged when it collided with a tree. Postaccident examination revealed that the air induction box contained a piece of bunched up paper that likely restricted the inlet cavity. As part of the annual inspection, a repair person completed a small fiberglass patch and painting on the lower cowling. He could not recall the specific repair on the airplane but said he often placed paper in the induction to prevent debris from entering the engine. After the maintenance, the airplane sat for a day with the lower cowling not fastened but maintenance personnel did not recognize the blockage. They also did not find the paper during the post-maintenance inspections and returned the airplane into service with an unsafe condition. Source: NTSB Aviation Accident Database Retrieved: 2026-02-12
NTSB Findings
Hierarchical cause / factor breakdown from the FAA bulk avdata database. Each finding tagged C (Cause) or F (Factor).
- — Aircraft-Aircraft power plant-Power plant-Air intake-Inadequate inspection
- — Personnel issues-Task performance-Maintenance-(general)-Maintenance personnel
Verbatim from NTSB's published report. Source file
NTSB_2020_WPR20LA180.txt.
Findings + structured fields enriched from FAA avall.mdb.
Full investigation docket on
data.ntsb.gov ↗.
Beyond the agency record
Search this event elsewhere.
Pre-filled searches into the sources where news + community discussion of aviation events lives. External sources are reported, not agency. Treat them as signal that something happened, not as fact about what happened.
Entity-clustered aviation events in the press — last 24 hr + 30-day archive.
Official agency record + docket.
Investigative docket: factual reports, photos, transcripts.
Long-running aviation incident database (Flight Safety Foundation).
Community NTSB synthesis blog — often has photos and witness reports.
Gold-standard aviation incident blog.
Aviation industry news search.
GA pilot forum — informed but rumor-prone.
GA pilot subreddit search.
Tail-number page — flight history (free tier limited).
AOPA Air Safety Institute search.
Mainstream press coverage. Recent events only.
Privacy-preserving news search.
External links open in a new tab. We don't ingest their content; we deep-link search queries.
Related research
What the literature says.
Academic papers and agency reports matching this event's aircraft type or causal vocabulary (stall, maintenance). Sourced from NASA NTRS, NTSB Safety Studies, FAA CAMI, AOPA Air Safety Institute, Embry-Riddle Scholarly Commons, arXiv, and the Semantic Scholar academic graph.
- Embry-Riddle Scholarly Commons 2023 · Conference paper
The Value of Strong Partnerships to Build a Successful Aviation Maintenance Career Pathway Program for Transitioning Military Service Members
The aerospace industry is competing with other industries for a qualified workforce, and many of those competing industries are investing heavily in creating workforce development pipelines.
- Embry-Riddle Scholarly Commons 2026 · Journal article (IJAAA)
From Reactive to Predictive: A hybrid Trust-Mediated Adoption Framework for Data-Driven Maintenance in Distributed-Authority Aviation Environments
Modern aviation maintenance operates within increasingly data-intensive technological environments, yet the operational integration of predictive maintenance into routine decision-making remains incon…
- NASA NTRS 2026 · Conference Paper
Computational Analysis of Steady State Aerodynamics of Transonic Truss-Braced Wing Configuration in Deep Stall
This study presents a computational investigation of steady state aerodynamics of the Subsonic Ultra-Green Aircraft Research (SUGAR) Transonic Truss-Braced Wing (TTBW) configuration over a wide range …
- Semantic Scholar 2025 · Article (Applied Sciences)
Decision-Making Framework for Aviation Safety in Predictive Maintenance Strategies
The implementation of predictive maintenance (PM) in aviation presents unique challenges due to strict safety requirements, complex operational environments, and regulatory constraints.
- Embry-Riddle Scholarly Commons 2024 · Journal article (JAAER)
Low-Resource Automatic Speech Recognition Domain Adaptation – A Case-Study in Aviation Maintenance
With timeliness and efficiency being critical in the aviation maintenance industry, the need has been growing for smart technological solutions that optimize and streamline the different underlying ta…
- Embry-Riddle Scholarly Commons 2024 · Journal article (JAAER)
A New Trajectory in UAV Safety: Leveraging Reinforcement Learning for Distance Maintenance Under Wind Variations
In the field of aviation, safety is a critical cornerstone, and the operation of Unmanned Aerial Vehicle (UAV) systems is deeply connected with this principle.
Browse the full corpus — academia portal ↗