ASI Safety Tip: Hot Starts

[WannFly]

 

[denverpilot]

See what you get for switching to a Lycoming 182?

 

[Sam D]

The video was incomplete. There was no discussion of rubbing rabbits feet or burning sage.

 

[Capt. Geoffrey Thorpe]

Just amazing how **** poor "aviation quality" really is. If an auto company made cars this hard to start, they would go out of business in a week.

 

[luvflyin]

Just amazing how **** poor "aviation quality" really is. If an auto company made cars this hard to start, they would go out of business in a week.

I was thinking how poor some video sound mixing is. Catchy tune, but for gawds sake it didn't have to be over his voice the whole dam time. Oh yeah, good primer on hot starts. Before you ask, the pun hit me just after I typed it, not before

 

[kgruber]

He speaks of "mixture out." Means little as a technical term.

Should be saying "Mixture............Idle Cutoff."

 

[asicer]

See what you get for switching to a Lycoming 182?

Hot start is a problem on the ground. Carb ice is a problem in the air. Which would you rather deal with?

 

[kgruber]

As a floatplane pilot....................carb ice any day.

 

[denverpilot]

Hot start is a problem on the ground. Carb ice is a problem in the air. Which would you rather deal with?

Carb ice. Pull the handle and it doesn’t happen and it doesn’t delay an entire flight, ever. The carb heat on the Continental is very effective.

 

[GRG55]

...The carb heat on the Continental is very effective.

And it needs to be.

 

[hindsight2020]

For the FI folks, they tend to have a poor understanding of their fuel delivery system, which doesn't help when it comes to simplifying the process of hot starting a FI engine. In general, Conti setups have return lines to the tanks because the mechanical/electric fuel pumps are designed to overfeed the engine. Lycomings in general do not have return lines because the pumps are not designed to overfeed the engine like Conti pumps do. And by overfeed we mean over-rich condition that kills the engine in the absence of return lines. The fuel injection metering system of the Lycos is different than Contis in this regard, which drives the difference in that fuel overfeeding, or lack thereof.

At any rate, the significance of the return lines is important because it is that feature that allows the Conti FI setup to purge the intake lines without flooding the cylinders. This is accomplished by using the electric pump with the mixture in cutoff. This action circulates fuel through the mechanical pump and purges the vapors back to the tanks via the return lines. Continental recognizes some leak (it's a conti after all...) will occur past their mech pump by that pressurization of the lines even while in cutoff, which acts as an incidental priming of the intake lines past the mech fuel pump. An accidental side benefit that generally leads to not having to re-prime the engine with the cold start procedure, after said purging action has been attempted.

Lycoming FI setups otoh do not have said purge lines. Activating the electric pump with the mixture in cutoff does nothing for the cooling of the mechanical pump and the vapors aft of the spider, since no circulation of cold liquid fuel through the culprit components is occurring like it does in the Continental FI fuel system setup. This is why FI Lycos are known for being harder to hot start than the FI Continental. In frustration, some Lyco owners outright flood the engine on purpose (run electric pump with the mixture out of the cutoff position) then directly proceed to the flooded start procedure. I personally don't advocate for that course of action, but I've seen it done.

Ultimately, this also assumes a perfectly healthy impulse coupling/SOP system. I almost burnt out a starter in my Warrior (a carb setup mind you) the week after I bought it, since the seller didn't disclose a weak impulse coupling and masked the starting woes by flying the airplane before I arrived for the flight test. At any rate, that can manifest itself as a real problem where otherwise you're doing nothing wrong wrt the starting procedure. So one has to make sure the impulse coupling is strong, otherwise you're gonna have issues while blaming it on hot starts, when you go for that quintessential afternoon trip to the fuel pumps in the Texas heat.

Carb setups of either brand are otherwise very resilient to hot start because the carb is usually cold, and the mixture doesn't flood the engine to the degree FI pumps (mechanical or otherwise) do, nevermind no fuel circulates unless that vacuum is operating (aka crank turning). I still personally prefer hot start woes to carb icing, but that's my prerogative in ownership.

Indeed, a better electronic metering system would largely be able to optimize the fuel/air ratios and make these machinations no longer the purview of the pilot, but cost is a big inflection point in this hobby, so I deal with what I can afford. When I go EAB then I can wax poetic about what I can do something about. As of right now I'm captive audience, so it's either quit until I can flow to 2 seat EAB, or accept the sunk cost.

As a FI Lyco owner, I haven't been stuck off station on account of hot starts. I don't pretend to suggest they're not legitimate harder to hot start compared to my Warrior or Continental FI. It hasn't been a non-starter for me though (pun very much intended ). Weak batteries otoh have gotten me in a pickle however, which is why I don't own 28V airplanes. I find the 12V automotive jump starting capability a pre-requisite to my XC flying. And I can put a $ figure on it, based on what I've seen FBO callouts for things like batteries or alternators run people when away from home. I digress.

 

[GRG55]

...Lycoming FI setups otoh do not have said purge lines. Activating the electric pump with the mixture in cutoff does nothing for the cooling of the mechanical pump and the vapors aft of the spider, since no circulation of cold liquid fuel through the culprit components is occurring like it does in the Continental FI fuel system setup. This is why FI Lycos are known for being harder to hot start than the FI Continental. In frustration, some Lyco owners outright flood the engine on purpose (run electric pump with the mixture out of the cutoff position) then directly proceed to the flooded start procedure. I personally don't advocate for that course of action, but I've seen it done...

My Lycoming hot start procedures works fairly reliably on my two fuel injected engines. Throttle cracked open, prop full forward, mixture at idle-cutoff. Auxiliary fuel pump on, mixture to full rich for three seconds and then back to idle-cutoff, electric fuel pump off. Crank the starter and as soon as it catches advance the mixture smoothly.

 

[asicer]

My Lycoming hot start procedures works fairly reliably on my two fuel injected engines. Throttle cracked open, prop full forward, mixture at idle-cutoff. Auxiliary fuel pump on, mixture to full rich for three seconds and then back to idle-cutoff, electric fuel pump off. Crank the starter and as soon as it catches advance the mixture smoothly.

My Lyco hot start goes like this (I think I actually learned this from here on PoA)...
Shutdown: 1000RPM, mixture ICO, mags off, master off, beacon off.
Post-shutdown: Don't touch anything!
Hot start: Beacon on, master on, engage starter. When it starts to fire, smoothly advance the mixture to full rich.

So far it's never failed on the M20F, DA40, C172S and C182S/C182T. It's also taught me more respect for handling the prop when I'm pushing the plane.

 

[Checkout_my_Six]

nice video.....

but, none of that will work on my aircraft.

 

[MooneyDriver78]

My Lyco hot start goes like this (I think I actually learned this from here on PoA)...
Shutdown: 1000RPM, mixture ICO, mags off, master off, beacon off.
Post-shutdown: Don't touch anything!
Hot start: Beacon on, master on, engage starter. When it starts to fire, smoothly advance the mixture to full rich.

So far it's never failed on the M20F, DA40, C172S and C182S/C182T. It's also taught me more respect for handling the prop when I'm pushing the plane.

I would leave the Beacon on, so at a casual glance you know if the master is still on.


Tom

 

[wilkersk]

For the FI folks, they tend to have a poor understanding of their fuel delivery system, which doesn't help when it comes to simplifying the process of hot starting a FI engine. In general, Conti setups have return lines to the tanks ...

Gosh that sounds familiar. Like possibly from a book I read.... ;-)

 

[Checkout_my_Six]

For the FI folks, they tend to have a poor understanding of their fuel delivery system, which doesn't help when it comes to simplifying the process of hot starting a FI engine. In general, Conti setups have return lines to the tanks because the mechanical/electric fuel pumps are designed to overfeed the engine. Lycomings in general do not have return lines because the pumps are not designed to overfeed the engine like Conti pumps do. And by overfeed we mean over-rich condition that kills the engine in the absence of return lines. The fuel injection metering system of the Lycos is different than Contis in this regard, which drives the difference in that fuel overfeeding, or lack thereof.

this is the place where generalities will not work.....mine has the return but the pump is setup differently....so your suggestions will not work.

If you see a turbo Bonanza with the cowling up....me...you'll know why. The only thing that aids hot starting for me is prevention.