Life has a way of throwing problems at you when you least expect them, and having an engine cowling open up in flight is just one of those problems. Because we use our preflight checklists, having a cowl open up doesn’t happen very often, but when it does….
The Problem: Your engine cooling depends on having that cowl door closed. With the engine cowling open, your cylinders may overheat, and damage may occur. Worse yet, when the cowl opens (depending on your workload) the problem may not be immediately obvious. This is because the door will probably not fly up as you might expect. Most often, what most people see is the cowl goes into what is called “trail” that is, it seems to hover above the normally closed position.
In-Flight Strategy: First, Fly The Plane. Losing your head for minor problems like this is an almost sure-fire way to make a critical mistake. Next, following the procedure for landing in your POH, Reduce Power and look for a place to land. Reducing power gets the majority of the damaging heat production stopped, helping to protect your engine. Get your speed back to your best glide speed – but react practically. If a certain airspeed/angle of attack causes the door to flap violently pick a different speed, but be aware that your options may change accordingly. When you have the airport in sight, make a normal approach and land out normally.
After a safe arrival, taxi to a safe location, and inspect the aircraft for damage. If you were unlucky and lost the cowl door, you will probably need to get a new one before you can safely fly again (unless your aircraft is certified for flight without the particular missing door.) Finally, try to figure out what caused the door to open. One thing is for sure: if you don’t find the reason for the cowl door flying open before you take off again, chances are that the same problem will happen again.
If you find the problem and your inspections reveal no damage, check your oil, close the cowl door, check your fuel, do a thorough run-up and (if everything appears normal) get back in the air — carefully. When you are in the air, keep an eye on your engine instruments to look for readings that may indicate a problem. When you get to your home airport, have your regular mechanic take a look at the plane for other problems you might have missed.
BOTTOM LINE: Living through having a cowl door open in flight is pretty easy. All you need to do is keep your head, avoid panic, and fly the plane. Using these simple concepts will get you and your passengers back on the ground quickly and safely.