RV Cold Starts

[Colonel]

So I’m walking across the rows of hangars for the pre-flight piddle at the bathroom.

Around the corner, out of my line of sight I can hear an aircraft start. Four cylinder Lycoming, I can tell it’s new, and I can tell it’s an RV because the guy beats on it with 1500 RPM right away in some attempt to destroy his piston skirts. Sure enough, I turn the corner and it’s an unpainted nosewheel RV of some kind.

Why is that? I travel thousands of miles and the same people are hating on their engines.

[Squaretail]

Because people are the same everywhere. Boringly, depressingly the same.

[Colonel]

Ok. This is what happens when you fuck a Lycoming up with too much RPM after cold start.



Note that the piston has expanded far more rapidly than the steel cylinder. Both the piston
skirt and cylinder wall are badly damaged. Zoom in and look at the oil scraper ring. It is
full of aluminum. How well does an oil scraper ring work, if it's full of aluminum rubbing
against a scored cylinder wall?

Bonus points for off-the-scale irony: after abusing and damaging their engines, these
wankers sit around and complain that they they don't like flying single engine at night
or in cloud because they don't trust their engines. Well, maybe if they didn't fuck them
up, they'd work better? Are all pilots starved of oxygen at birth, or just most?

These wankers are the cream of the crop. One guy at my old airport that hated on his
RV engine had a PhD. CSIS. He kept Canada safe. I wouldn't let him push my lawnmower.

Now, this is how you start an engine.



Not me, my kid.

Below 1000 RPM for at least one minute after cold start.

Now, I know people think I'm a moron that doesn't know anything about aviation, but
if I speak too quickly or use any words you don't understand, please speak up.

PS No one gives a fuck, but look at the delay between the left mag and right mag
at start. That's the Bendix starter switch, grounding out the right while the starter
is engaged.

[Squaretail]

Are all pilots starved of oxygen at birth, or just most?

Probably is the cause of them wanting to be pilots in the first place. I mean if you have a hankerin’ to hang out with some weird people, you can’t miss at an airport.

[Colonel]

if you have a hankerin’ to hang out with some weird people, you can’t miss at an airport.

Your new signature?

I know the irony is dripping here, but yes. You might meet the nicest people on a Honda (see 1960's ad)



but you are going to meet the weirdest people outside of an asylum at an airport. I have no idea why that is. My airport shirt:

[Squaretail]

That's an awesome Van Hagar shirt.

[Slick Goodlin]

Funny, I was chatting about the care and feeding of a small Lycoming just a few days ago. I don’t own one, but he does and he flies a good bit. He’s a pretty clever guy and one not afraid to track down the right people to help him better understand how to get the most out of his airplane and engine. Imagine my surprise when he said that he’d heard there’s such a thing as too little RPM immediately after start. The idea being that the very lowest RPM delays oil delivery up to the cam and lifters.

I don’t have a horse in this race but it sounds like there must be a sweet spot somewhere in the middle. Meanwhile I think I’m going to do an oil change on at least one A40 this week and slip a little Camguard into the new stuff.

[Colonel]

Wanna see real-time (3 samples per second) logged engine data showing oil pressure ramp up at low RPM?



at 500 RPM, that AEIO-540 went from 0 psi to 80 psi in 2 seconds (14:28:16 -> 14:28:18) in a cold start.

Let's look closely at the pulses from the magnetos during that time period:



Cranking occured 14:28:12 -> 14:28:13 (for 2 seconds) - we know that because the right mag is grounded.

Start occurs at 14:28:14. Oil pressure goes from 0-80 psi during 14:28:16 -> 14:28:18, cold start.

And that's the super-thick W120 that my son is partial to (for RPM control), which is pretty much worst case.
Thinner oil would ramp up even faster (eg any multi-viscosity cat piss).

So. Is 2 seconds 0-80 psi cold start too slow an oil pressure ramp-up at 500 RPM? What is your acceptable metric? One second?

I would be glad to see your buddy's real-time logged data. And his pistons and cylinder walls and bearings.

For guidance on this subject, see the Lycoming AEIO-360/540 Aerobatic Engine Operator's Manual p/n 60297-21.





Those are some pretty generous time periods.

Anyways, the world is full of bullshit which is quickly exposed by good data. Please let me know if you think
the above oil pressure ramp-up is not adequate. Lycoming thinks it is.

[dumbbell daddy]

I always get a chuckle out of the RV guys. It’s funny. Van originally intended people to build his airplanes light and crisp with rebuilt engines, basic 6 pack, used avionics and bucking bars and rivet guns. Some of these RV’s almost look like they mimic an Airbus cockpit.

[Colonel]

The world seems full of phonies, pretending to be something they are not.

What’s wrong with being who you are?