RV8 - Final Report - N6948L

[A2022]

RV8 Preliminary Report - N6948L

well, we don't know much about this one yet except that he didn't make it out alive. build and maintain the aircraft as if your life depends on it, because it does. no innocent passengers, did not harm anyone on the ground, doing what he liked to do. just need to clean up the mess.

The aircraft, an experimentally David B. Lunn kit-built Van's RV-8, N6948L, was destroyed when it crashed and caught fire shortly after takeoff from Corona Municipal Airport (KAJO), Corona, California. The sole pilot onboard sustained fatal injuries.

https://aviation-safety.net/wikibase/348884

[A2022]

well, the pilot didn't appear to have sound judgement for the takeoff if the engine was sputtering. flying with a dry tank limits the options and perhaps exposes a problem if the fuel selector valve has a small air leak to the opposite side. just need to clean up the mess.

In my opinion, it is not wise to ever run a tank dry in these small homebuilt aircraft. vacuum is present at the fuel selector valve and is needed to draw fuel from the tanks. if there is a slight air leak in the selector valve and the opposite side tank is dry, air can be drawn into the system instead of fuel, starving the engine of fuel. maximum vacuum at the selector valve is present during takeoff where there is maximum fuel flow. the fuel selector valve is a liquid valve, not an air valve.

edit: as part of my flight-testing program, I conducted min fuel testing at 2000 ft AGL over an airport. round and round until the engine stumbles. for routine operation, I never run a tank dry.

https://data.ntsb.gov/carol-repgen/api/ ... 193532/pdf

The pilot had flown the airplane to Corona on November 13, 2023, for the purpose of having it painted there. The accident flight was the first flight after it was painted. The paint shop required the pilot to disassemble and reassemble the airplane before and after the painting because it was a homebuilt airplane. The pilot intentionally chose to leave the left fuel tank empty because it was drained from being repaired prior to flying the airplane to Corona. The pilot did not refuel the airplane after it was painted. Witnesses reported hearing the airplane during the takeoff and remarked that the engine sounded as if was “missing” and producing partial power.

A review of the recorded security camera footage at the airport revealed that the airplane came into the frame at 11:49:23 when it was midway down runway 07, (passing by the fuel tanks) showing the wheels had not yet lifted from the surface. The airplane continued down the runway and rotated about 4 seconds later. Based on the distance and time, the airplane’s speed was calculated to be 71 kts at the time of rotation and a sound spectrum analysis revealed that the engine rpm was about 2,500 at that time. The airplane climbed slightly, just passing over a berm at the airport’s perimeter reaching a maximum altitude of about 95 ft above the runway. The estimated ground speed was 58 kts. Thereafter, the airplane descended and made a left turn, disappearing from the frame (see Figure 1 below).




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DAVID B LUNN, RIP, perhaps your experience can save another.

[A2022]

RV8 - Final Report - N6948L

Well, what else can you say about this chain of actions and events except that Darwin always prevails?

https://data.ntsb.gov/carol-repgen/api/ ... 193532/pdf

Shortly after takeoff, the airplane climbed to about 95 ft above ground level and then made a shallow descent and turned left. The airplane collided with a road and hit a berm before becoming engulfed in flames. Witnesses reported that the engine sounded like it was producing partial power.

The pilot had flown the airplane to the departure airport about a month before the accident to have it painted at a shop there. The accident flight was the first flight after it was painted. The left fuel tank was likely empty because the pilot had drained and repaired it before flying to the airport, and no evidence was found of the airplane being refueled at the airport. Based on his receipts, the pilot had used an alcohol-resistant gas tank sealer to repair the fuel tank.

Postaccident examination of the fuel system revealed a hardened white material throughout the fuel system, including in the fuel filters and the mechanical fuel pump. The material was analyzed by the NTSB Materials Laboratory to determine its chemical composition. The tested samples were consistent with materials in the alcohol-resistant gas tank sealer.

Based on the presence of hardened white material throughout the fuel system, the pilot likely applied the gas tank sealer improperly. The sealer manufacturer stated that if the tank is not dry before applying the sealer or has foreign matter, it may prohibit the sealer from adhering and then lead to it coming loose, eventually entering the fuel system and blocking the fuel pump. In addition, if the airplane was refueled after the sealer was applied but not fully dried, any liquid sealer remaining in the tank likely would have coated the fuel system components as found after the accident.