Aero-Tips!

A good pilot is always learning -- how many times have you heard this old standard throughout your flying career? There is no truer statement in all of flying (well, with the possible exception of "there are no old, bold pilots.")

Aero-News has called upon the expertise of Thomas P. Turner, master CFI and all-around-good-guy, to bring our readers -- and us -- daily tips to improve our skills as aviators. Some of them, you may have heard before... but for each of us, there will also be something we might never have considered before, or something that didn't "stick" the way it should have the first time we memorized it for the practical test.

Look for our daily Aero-Tips segments, coming each day to you through the Aero-News Network.

Aero-Tips 08.02.06 (5) red underline -- headers 5 regular

One of the most critical components to engine temperature management, and one of the most commonly forgotten items in high-performance engine operation, is the cowl flaps. Cowl flaps can profoundly affect long-term health and longevity of a high-performance airplane engine - making it even less likely to reach the factory recommended Time Before Overhaul (TBO).

Cowl flaps are movable extensions of (usually) the lower engine cowling that open or close to deflect the slipstream. When open, cowl flaps deflect the slipstream and create an area of low air pressure below the engine compartment. This draws air through the cowling air inlets and across the cylinders, helping dissipate the heat of combustion.  It's especially important that cowl flaps be open during high power operation at low forward airspeed-such as takeoff and climb. In cruise closed cowl flaps create a smaller low pressure area, but one still adequate for cooling at high indicated air speeds.

Note: Open cowl flaps in cruise increase airflow through the engine compartment, which also increases "cooling drag" (increasing at the cube of the indicated airspeed). In many models, leaving the cowl flaps open in cruise may cost five knots or more in top-end airspeed.

Here's an easy mnemonic for remembering cowl flap use:

• C is for Checklists: Use printed checklists -- start-up, climb, cruise, descent and after landing.
• O is for Open cowl flaps for start-up, taxi, run-up, takeoff, climb and for taxi-in after your clear the runway.
• W is for Watch cylinder and oil temperatures and close the cowl flaps as the aircraft approaches cruise speed in level flight. But if the engine is getting abnormally hot, or you're in a configuration where it's likely to get hotter (taxi, takeoff or climb), open the cowl flaps.
• L is for Leave the cowl flaps closed for descent and landing.

Aero-tip of the day: Take care of your engine by properly using the cowl flaps.

FMI: Aero-Tips