Engine Shutdown Procedure

zman · #1 09-21-2009, 11:08 AM

Anyone have any thoughts on the following procedure for engine shutdowns...

While at the Reno Air Races this last weekend (in the pits)...I noticedthat
many of the race aircraft after the race and taxi back ran-up there engines to a intermediate RPM for about 30 sec then cut the mixture to shut down the engine while at the higher RPM...I am guessing it was to keep the spark plugs hot an clean...I have and XP IO-360 on my RV-8 and think that this may be a better way to shut down and engine after a days flight...a run-up to 1500-1800 RPM then after 20-30 seconds... Mixture-Idle Cutoff...Any thoughts??

Zman

T6pilot · #2 09-21-2009, 11:15 AM

The procedures for large radials/liquid cooled Merlins are different than for Lycomings. Recommend you go to the Lycoming website and obtain a copy of their operational procedures manual. It provides procedures for operation including shutdown. You generally can't go wrong following the OEM procedures. Fly Safe.
Randy

Mike S · #3 09-21-2009, 11:24 AM

Oil scavenging for dry sump, at least for the radials.

wera710 · #4 09-21-2009, 11:28 AM

On the Lyc its not a bad idea to lean aggressively on the ground once you are taxing back to the hanger. Then, before shut down, run her up to about 1200 rpm for 20 or 30 seconds, then go to idle cut off. They lycomings run pretty rich on the ground.

plehrke · #5 09-21-2009, 12:22 PM

If you lean agressively on the ground you do not need to bring the temp up (increase rpm) just before shut down (my opinion). I lean to the point of engine dying (and then push in a tad) while taxing in and out from a flight. Never have had spark plugs fouled or rough run-ups.
Leaning or running up is done to get the temps up to allow a better burn and activate the lead scavaging agents in the fuel. I have heard that you want to get the EGT to over 1100F. Lycoming recommends the run-up to 1800 rpm for 15-20 sec. See page 66 of the Lycoming Flyer (page 32 of the pdf file)

jetjok · #6 09-21-2009, 12:29 PM

The reason for the run-up on radials and the Merlins is to scavenge the oil from the lower end of the engine prior to shut down. These engines have "dry sumps" meaning that they have a remote oil tank.
It looks and sounds cool, but we certainly do not need to be doing that with our Lycoming's for the reasons stated in previous posts.

Quote:

Originally Posted by Mike S

Oil scavenging for dry sump, at least for the radials.

SteinAir · #7 09-21-2009, 12:39 PM

Not only for oil in the sump, but many Ham Standard c/w props also recommend shutting down in high pitch which also forces the oil out of the cylinder and back to the tank along with all the other oil being scavenged back to the tank.

Me in the RV....most of the time I just pull the mixture as I'm rolling up to my hangar. By the time I reach the hangar the engine is stopped and if I do it right I'll have exactly enough momentum to just swing the tail around ready to push in the hagar!

Cheers,
Stein

Mike S · #8 09-21-2009, 12:41 PM

Quote:

Originally Posted by SteinAir

Me in the RV....most of the time I just pull the mixture as I'm rolling up to my hangar. By the time I reach the hangar the engine is stopped and if I do it right I'll have exactly enough momentum to just swing the tail around ready to push in the hangar!

Cheers,
Stein

Trained by Bob Hoover????

Mike S · #9 09-21-2009, 12:44 PM

Just a tip for those who fly with mags---

Right before you shut the engine off, at idle, shut the ignition off for a short while, just a quick off, and then back on. Then use the mixture to shut it off as normal.

If the engine FAILS to shut off while the ignition is off, you have a bad mag ground ---"P"---lead, and a HOT mag.

Fix it soonest, a hot mag can really spoil your day.

rv9av8tr · #10 09-21-2009, 02:02 PM

Turning mags off on a running engine, then back on can cause a **** of a backfire. I'd strongly suggest only doing one mag at a time.... don't turn both mags off at the same time. "Been there done that"