The Survival Rate

Out of 8,817 total E-AB accidents, 2,831 involved engine-related problems — about 32% of all accidents. Of those, 469 were fatal. That means 83.4% of pilots who experienced an engine failure survived.

The engine quitting is not what kills you. What kills you is not having somewhere to land, or stalling while trying to stretch the glide back to the runway. If you have a field within gliding distance and you fly the airplane all the way to the ground, you will almost certainly walk away.

What Actually Causes Engine Failures

Here is every engine-related initiator in the dataset, ranked by frequency:

PILOT = fuel mismanagement (pilot error, not mechanical). BUILDER = builder construction/installation error.

24% of Engine Failures Are Actually Fuel Mismanagement

This is the number that reframes the entire engine failure conversation. Out of 2,831 engine-related accidents, 685 were caused by the pilot running out of gas (fuel exhaustion), selecting the wrong tank or having a fuel flow blockage (fuel starvation), or using contaminated fuel.

Fuel exhaustion means the tanks were empty. The pilot either miscalculated endurance, did not check fuel before departure, or pressed on when they should have stopped for gas. Fuel starvation means there was fuel on board, but it was not getting to the engine — often because the pilot had the wrong tank selected or a valve was in the wrong position. Neither of these is the engine’s fault.

If you subtract fuel mismanagement from the engine failure count, the “true mechanical” engine failure number drops considerably. The engine is more reliable than the headline number suggests — but only if you feed it properly.

Truly Mechanical Failures

The genuinely mechanical engine failures — internal failures, oil system problems, ignition failures, drive system issues, and the undetermined category — account for 1,788 accidents with 302 fatals (16.9% fatal rate).

The “undetermined” category is the largest single bucket, which is frustrating but honest. In many engine failure accidents, the NTSB cannot determine the exact cause — the engine is too damaged, or the investigation does not have enough evidence to pinpoint the failure. Some of these are probably mechanical, some are probably fuel-related, and we simply do not know.

Builder-Caused Engine Failures

Builder installation and construction errors caused 358 engine-related accidents (57 fatal) — roughly 13% of all engine incidents. These include improperly plumbed fuel systems, bad ignition wiring, incorrectly installed propellers, and inadequate oil cooling setups.

This is the risk that is unique to homebuilts. A certified aircraft has its engine installed by mechanics working under an approved process. A homebuilt has its engine installed by... you. If you are building, this is where peer review from your EAA chapter, a visit from a designated airworthiness representative (DAR), and rigorous testing during phase I pay off.

The fuel system is the most common builder error category. Get the fuel system inspected by someone with experience. A bad fuel line routing, an undersized vent, or a poorly placed fuel selector can turn a perfectly good engine into a glider at the worst possible moment.

Which Engines Are Most Reliable?

Engine-initiated percentage measures how often the engine was the starting cause of an accident. Lower is better — it means the engine is less often the reason things went wrong.

Engine-initiated % = percentage of that engine type’s accidents where the engine was the starting cause. Full engine analysis

A Word on Auto Conversions

Automotive engine conversions (Corvair, Subaru, Volkswagen, etc.) consistently show the highest engine-initiated accident percentages in the data. This makes intuitive sense: these engines were designed for cars, not airplanes, and the conversion process introduces variables — reduction drives, different cooling requirements, modified fuel systems — that purpose-built aircraft engines do not have.

That does not mean auto conversions cannot work. Many builders fly them safely for thousands of hours. But the data says they have a higher probability of causing an accident than certified aircraft engines or purpose-built engines like the Rotax 912. If reliability is your priority, the data points toward Rotax.

Surviving a Forced Landing

The 83.4% survival rate for engine failures tells a clear story: most forced landings are survivable. The ones that are not share common factors:

• No suitable landing site within gliding distance. Flying over mountains, dense forest, or urban areas with no emergency options is the biggest risk multiplier.
• Trying to turn back to the runway.The “impossible turn” after takeoff continues to kill pilots. Unless you have altitude and have practiced it, land straight ahead.
• Stalling while stretching the glide. You lose an engine, see a field that is almost within reach, pull back to stretch it, and stall. The airplane can glide — but only if you let it.
• Night or IMC. Forced landings in daylight over open terrain have a very high survival rate. At night or in clouds, the rate drops dramatically.

The practical takeaway: always have a field in range. On every flight, continuously scan for emergency landing options. When flying cross-country, route along roads and valleys rather than directly over ridgelines. And practice power-off landings regularly — the skill is perishable.

The Bottom Line

Engine failures in experimental aircraft are common enough that you should plan for one. But they are survivable the vast majority of the time. The data shows three clear ways to reduce your risk:

1. Choose a reliable engine. Purpose-built aircraft engines (Rotax 912/914, Lycoming, Continental) have lower engine-initiated rates than auto conversions.
2. Build the fuel system right. Have it inspected. And then manage your fuel properly in flight — check your quantity, switch tanks on schedule, and never assume you have more than you do.
3. Always have a place to land. Route planning is accident survival planning. The pilot who dies in an engine failure is almost always the one who had nowhere to go.

Explore more: Engine type comparison | All aircraft types | Risk calculator | Are kit planes safe?

Important Caveats

• The “engine undetermined” category is large because many engine failures cannot be root-caused by the NTSB investigation.
• Engine-initiated percentage depends on the aircraft types that use each engine. A Rotax 912 is typically in a slower, more forgiving airframe than a Lycoming IO-540.
• Survival rates are for the accidents in the NTSB database. Minor engine issues that did not result in an NTSB-reportable event are not captured.
• This data should inform your engine choice, not dictate it. Consult experienced builders and A&P mechanics for your specific installation.