Comp Air 7
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COMP AIR 7 - "Performance That Knocks Your Socks Off"
Text by Norm Goyer -- Photos by Bill Fedorko

Before you start the engine, be sure to apply the parking brake and stand on the brakes as well, because when those huge props start rotating, you can really feel the power, and you don't want the plane to roll until you're ready. To prevent surges, be sure all the power switches and navaids are off and the circuit breakers are in. Check all the controls to see if they're free and not binding.

The following is the procedure we used to start this Walter turbine (one not equipped with an auto-start assembly): Check the fuel valve once more to make sure it's on. See that all circuit breakers are in and that the generator is off. Pull the start lever on the power quadrant full aft to 'fuel cut off.' Position the propeller lever in the full-feather position. The last power quadrant lever is the power lever, which is placed in the idle position. Now you're ready to go. With one hand on the power level, use the other hand to turn on the master switch. Check the voltage to make sure there's at least 24.5 volts. To be absolutely sure, press the two test lights-one marked beta, the other marked limiter. Check the two igniters, one and two, then shut them off again. Now start the fuel boost pump and check to make sure there's at least 15 pounds per square inch. Then clear the prop area.

It's time to hit the starter switch. When the gauge shows N1, move the fuel lever to the start position. Turn both igniters on, and torch the engine on for two seconds, then off for two seconds. You must also monitor the ITT heat gauge to make sure it does not exceed 735 degrees, and keep the starter engaged until the engine reaches an N1 of 45 percent. Scan the oil pressure and temperature. When you've made sure the engine has reached 45 percent N1, you can release the starter. The next step is to check and see if the engine accelerates smoothly to 60 percent N1. Check again to make sure that you have not exceeded 735 degrees. If the engine does reach 735, you must pull the start lever to ICO (ignition cutoff) until the ITT drops below 650 degrees. This is the dreaded hot start that must be avoided to prevent damage to the engine. If the engine is running smoothly and all temperatures are in the green, you can switch the generator on, then switch the 12-volt buss on for the avionics. Make sure the radios and intercom are working correctly. Next, check the vacuum pump, strobes, beacons and lights.

It's finally time to taxi. The previous instructions might sound complicated, but they're really not. (They're similar to the start procedures of any high performance aircraft with a constant speed prop.) Release the parking brake, and use the prop beta control as the throttle. Avoid using too much brake or depending on the throttle; you have better and faster control with the prop lever. You're about to go for the wildest ride you've ever had -- unless you're an Air Force pilot flying an F-15 Eagle - and even then, the Comp Air 7 still has it beat on the takeoff run.

Takeoff is the same as with any high-performance taildragger, but with just a few more checks to make before you start the takeoff roll. Place the flaps 10 to 15 degrees down, recheck the fuel quantity and valve position, and make absolutely sure the fuel boost pump is on. Then, cycle the prop once or twice with the power lever in the idle position. Check one more time to make sure the power lever is in the run position. Set the power to 30 percent and slowly move the prop lever to the aft position, so you can check that the rpm are decreasing gradually. Now move the prop lever to the full-forward high-rpm position.

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Text by Norm Goyer
Photos by Bill Fedorko

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