Continental aircraft engine fuel system

Is anyone familiar with the 10-470 Continental engine? Specifically, the fuel system. When looking into a fatal crash at the local airport I found the preliminary report and it indicated that a “B” nut was not properly installed and when it vibrated loose the engine lost fuel pressure and power likely causing the crash. The report didn’t indicate that fuel leaked, only that fuel pressure dropped. Is there a fuel pressure regulator on that engine that is connected to the manifold to regulate fuel pressure. My searches for information regarding the engine leaves me confused as to whether it is carbureted or injected. And I was surprised that a modern 470 cubic inch aircraft engine only has 260 hp.

“And I was surprised that a modern 470 cubic inch aircraft engine only has 260 hp”

These engines are very under-stressed to maximize reliability.

As for what a ‘B’ nut is, I have no idea, but the ‘lost fuel pressure’ would make me think injection. But it could be something associated with a carbed engine’s fuel pump, too…

This question would be better answered on an aircraft site.
Unless, of course, it’s for some official reason, in which case you’ll need actual information from the manufacturer.

In searching the aircraft sites I find that I don’t speak the technical lingo to get beyond a home page, tsm. I’m as lost there as the soccer moms who post here with a CEL problem.

I tried calling my recip buddy, but he’s not there. I suspect that to identify the “B” nut would require some sort of exploded view drawing, parts list, or some other form of technical document. However, on the possibility that it’s a commonly used reference, I’ll ask him when I see him.

The “B” nut is simply a coupling nut between a length of steel or aluminum tubing most often used in fuel systems. My experience with them came from the earliest missile I worked on with a jet engine. Anyone that’s seen an engine with the cowling removed will instantly recognize the blue color. The “B” nuts on our Air Force missile engines were “safety wired” to keep the nuts from ever coming loose. If they did…jet fuel could spray out and catch the engine on fire or fuel pressure could be lost.

I added a picture of a “B” nut which merely stands for the second generation nut with a sleeve. The first generation nut (A) without a sleeve had a tendency to break or gall the copper tubes that were used in the open cockpit days. Not good when you were high in the sky with aircraft that did not glide very well.

@RodKnox…I believe the original 10-470 Continental engines had carburetors. A fuel injected version came out a couple of years later. The “B” nut was probably used on either version though. I’m not sure if civilian aircraft had the nuts safety wired or not. If they were then the only plausible explanation if they came loose would be that they were safety wired backward. I saw this a few times in the AIr Force when doing post maintenance inspections.

Well, something for @Rod Knox.

The Continental engine is an IO-470 as in Injected Opposed 470 cubic inch engine.

Since it is fuel injected there are fuel lines from the gear pump to the fuel controler and lines to the 6 individual injectdors. There are also air lines from the intake air venturi/throttle body to the controler that determine the fuel regulation pressure to send to the injectors. IIRC this is continuous injection system that works by adjusting the injection pressure to match the amount of air being ingested. I am going to refamilarize myself with how the mixture control is integrated with controler.

So when the ‘B’ nut vibrated loose the venturi signel was probably lost and the controler went to basic idle fuel control which would be an overlean condition at most throttle settings except idle. So if a suitable landing spot was unavailable, an off airstrip landing was probably made. Hopefully, it was not in IFR conditions or at night.

Those engines are rather primitive - max revs are often 3,000 while automobile engines of that size can go 5,000 easily .

Ask and ye shall receive. I guess if it was a fatal accident, then the guy didn’t have enough to get it on the ground again but if it was at the airport, he got close anyway. I guess thats why aircraft maintenance and repair is so stringent. Lose pressure on first street, no big deal, but a couple thousand feet in the air and you’ve got trouble.

The plane made a 180* about 1/4 mile after take off. The plane bounced off a road parallel to the runway and crashed into the front yard of a home. The pilot was dead at the scene.

@genex: “primitive” because they max out at 2700 rpm?

Direct-drive aircraft engines have RPM limited by the propellor, which is limited by the speed of sound at the tips. You can get better hp/cu in by gearing down, but then you have weight and reliability issues introduced by the PSRU.

Also, unlike an auto engine that outputs ~25% of maximum, an aircraft engine has to run at 75% in cruise.

Every so often, people kvetch about “1930’s technology” and try to get a 280-ish cu in auto engine to stand in for a 470 cu in aircraft engine. By the time you include the gearbox, coolant, radiator (with brackets), etc…you have an all-up weight and dimensions equal to or greater than the original…with “unproven” reliability (and teething problems from trying something new).

“Proven technology” actually a pretty effective solution to the application.

While I’m not much of a pilot, my understanding is that if an engine out situation occurs after takeoff you never try to turn around.
Nose down, straight ahead, and try to sit it down on anything halfway flat rather than bleed off a bunch of airspeed and possibly risk a tailwind by doing a 180. Sounds like both a mechanic and pilot error.

About 15 years ago Senator Jim Inhoff of OK (a licensed pilot) was flying along and the prop fell off of his plane. He sat it down safely and apparently the attachment bolts fell out after a bit of vibration. Nothing was ever revealed about any lack of safety wire or whodunnit… :wink:

Horsepower is dependent on RPM and aircraft engines tend to run at lower RPM than automotive engines…If you look at the torque numbers, you will see they are respectable…