Printer Friendly

Preheating: why and how.

Over the years, there have been almost as many myths and wives' tales about why and how to preheat an aircraft piston engine as there are people telling you how to land. Let's try to separate some fact from fiction.

LET IT FLOW

The primary reason to preheat an engine is to help ensure adequate lubrication as soon as the engine starts. Cold, congealed oil doesn't flow very well and greatly increased wear can occur in an engine until its oil is flowing smoothly. At the same time, the different alloys in the engine expand and contract at different rates. In extreme cases, close-tolerance components like bearings can contract with cold to eliminate any clearance between it and a crankshaft. Not only is this guaranteed to increase wear but it also prevents oil from flowing in the first place.

BLOW HARD?

Too often, we've seen a preheat session involve about 20 minutes of blowing propane-heated air into a cowling. That warms up the cylinders - maybe--along with the accessories, but doesn't do a thing for the oil. As this article's main text notes, aiming the heat source at the oil pan is critical to ensure thorough heating.

SLOW AND STEADY

Our preference is to use a slower, steadier method--which can be gas or electric--overnight. In any case, use a blanket, like the one pictured at top. Gas preheating systems like the one pictured in the middle photo definitely work faster than electric ones, but also can be cumbersome to transport and handle. Then, there's that pesky problem of carrying five gallons of propane in the cabin.

Instead, we prefer an installed electric system using heating bands around the cylinder bases, as pictured at bottom, plus at least one heating pad attached to the oil pan. This type of preheat system is simply plugged into a 120-volt AC source and allowed to work. Since it's already installed, there's nothing to lug around, except maybe a drop cord and a blanket, there's a very low hassle factor. The only better preheating systems we've found is a heated hangar or staying out of cold weather.

[ILLUSTRATION OMITTED]

[ILLUSTRATION OMITTED]

[ILLUSTRATION OMITTED]

COPYRIGHT 2012 Belvoir Media Group, LLC
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2012 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:AIRMANSHIP
Publication:Aviation Safety
Geographic Code:1USA
Date:Jan 1, 2012
Words:357
Previous Article:Winter flying lessons: some things about winter flying can't be learned from textbooks but only come from experience. Here are some examples.
Next Article:IFR emergencies: system failures under IFR must be handled differently than when the weather's good. Above all, remember to fly the airplane first,...
Topics:

Terms of use | Privacy policy | Copyright © 2019 Farlex, Inc. | Feedback | For webmasters