Aviation Safety Corner
GREETINGS! For this month's topic, I would like to conclude our discussion on, "Anatomy of an Engine
Failure." Examining the nature of power losses on takeoff and how they can be avoided. This is Part IV of
Let's begin our discussion with, "Preflight Strategies." We know all about annual and 100-hour inspections done by mechanics, but few of us seem to really recognize that the most important inspection of all is done by the pilot. So many of us gloss over the preflight by, maybe checking the oil and ducking under the wings momentarily. I've been guilty of it, and so, probably have you.
Now, let's focus on what is revealed by the takeoff-accident record; let's see what shouldn't be glossed over.
Fuel quantities. Many accident reports had notes similar to this: "Since fuel wasn't available at the airfield, the pilot departed for a nearby airport with, enough to make it that far. Some pilots used sticks to check their tanks; others didn't bother checking at all. Some knew their fuel gauges were unreliable and depended solely on their watches. All crashed.
Something that must be considered when you are low on fuel is that fuel moves to the low side of the tank when you rotate on takeoff. When you "stick" the tank, it is level. When you rotate for takeoff, al that gas moves to the back of the tank, and can leave the fuel feed port high and dry. The fuel in the lines is quickly used up at full power and, at around 100 feet, the engine sputters and dies. It's better to make arrangements to add several gallons of fuel than to risk ending up in a heap.
Check for fuel contamination and water. Fuel-testing devices are inexpensive and Readily available. Get one and use it before the first flight of the day and following each refueling. Check for proper fuel grade (color), no contaminants floating around (i.e., rust flakes, dirt, etc.) and of course, for water. And test all the aircraft sumps, not just the ones(s) at the engine(s); the engine sump may not show the water that was just pumped in by the line truck.
If you find anything questionable, go out to the wing tip and shake the airframe and/or push down on the tail until you get a good, nose-high angle. This can jar loose water and contaminants that didn't settle right next to the sump drain. Test again. If anything appears, maybe a better inspection of the tanks is required. (By the way, by performing these first two steps, you may have just decreased your chances of a takeoff power loss by over 30 percent).
Check the weather. It's likely that, during a briefing, you listen intently as the FSS specialist covers ceilings and winds, but yawn when the temperature and dew point are given. You shouldn't. That's your key to deciding whether you're in for a day of carburetor icing. It can be 90 degrees and sunny, but a muggy day can mean icing in the venturi.
Check your exhaust stacks. As pointed out previously, clean, light tan or gray exhaust stacks tell you that the engine is burning fuel efficiently. Black soot is indicative of excessive richness, and oil stains may be foretelling problems.
Check fuel vents. The biggest problems are ice build-ups and inspect nests. Listen for a rush of air when you remove the filler caps. Also, a small puff of air into the vent tube will usually determine if the tube is clear. A flashlight can aid in determining blockage near the end of the tube. Any hiss on the cap removal or resistance to blowing into the vent tube should be investigated. Check the owner's manual for any information on this.
Brief your passengers. It is pretty much standard procedure to give newcomers to flying a briefing prior to getting into the airplane. Indeed, most of us probably brief them all the way to the airport. Regardless, prior to boarding, it is a good idea to include specific instructions not to touch anything without asking first. Airplanes are completely foreign to newcomers, and, as the fellow with the camcorder found out, what looks like the vent knob on a '63 Chevy to them.
Now, let's discuss, "Before-Takeoff Tips". During starting, taxi and run-up, there are several things you can monitor to help determine engine health prior to takeoff:
Pay attention on start.
Stay below 1,000 rpm during the first few minutes of operation.
During the first few minutes of operation, avoid using excessive power to move the aircraft.
Be critical during the run-up.
It is important to note that if carb-icing conditions exist, and you have a long hold, waiting for traffic, or a clearance, following the run-up, it's cheap insurance to run up the engine a little and apply carb heat just prior to taking the active runway.
Now, In Conclusion, Remember operating an engine at higher power than necessary simply wears it out faster. Common sense dictates the use of power.
Don't miss next month's, Aviation Safety Corner, when we'll discuss, "Cocktails & Cockpit". Flying while intoxicated doesn't happen often, but when it does the results are usually tragic. A single DWI may point to trouble ahead in airplanes. This will be a Four Part Series.
Larry G. Harmon
FAA Aviation Safety Counselor