Sequim

L. Scott Brooksby, DDS, CFII,ATP,A&P, MEI

2022 Taylor Cutoff Rd

Sequim, WA 98382

702-274-6700

Check out our Sequim dental office at drbrooksby.com.

Private Pilot Ground School

Sequim Advanced Dental Office

680 West Washington #E102 (Next to Subway)

Sequim, WA 98382

Tuesday and Thursday from 5-7 p.m. Starting November 8, 2016

Cost $300 includes King Schools Private Pilot online course

Flight Planning at SkyVector.com

Multiengine Airplane Complexities

 

Because there is a second engine, and the engines are on the wings instead of on the fuselage of most multiengine airplanes, there are problems that must be dealt with.

The first consequence of more than one engine is that if you lose the engine you now have dead weight instead of lift on one side and the original lift on the good side. This can cause the airplane to roll into the dead engine and it begins to lose altitude as the nose drops from the extra dead weight. The good engine, being away from the center of gravity causes the engine to pull the airplane around the center causing adverse yaw. These effects are most pronounced when the airplane is slow and when it is near sea level and producing maximum power in the good engine.

On take off, if an engine is lost while on the ground, it can cause the airplane to pull off to the side off the runway.

Just after take off, especially if the airplane is slow this can cause the airplane to roll over on its back as it dives into the ground. The solution for this loss of engine power on take off is to pull the good engine back. On the ground this keeps you on the runway, but in the air you must immediately land straight ahead or bring the good engine back on line while nosing over to maintain and increase airspeed. Depending on the power available, landing straight ahead or continuing in flight is a decision that must be made immediately and correctly.

In Multiengine training we are required by the FAA through the Practical Test Standards to do what is called a Vmc demo. The book says that we are to start the maneuver at least 1500 feet above ground level. They want you to pitch up to reduce airspeed by one knot per second until the airplane begins to lose directional control or stalls.

The problem with this approach is that it teaches the student that Vmc situations happen gradually, they do not. It puts the aircraft near a stall with only one engine operational and is the number one cause of fatalities in multiengine training.

This approach should be abandoned. The best way to teach and practice a Vmc Demo is to set the airplane up about 10kts above the best single engine speed Vse. Place the feet on the floor, not on the rudders, pitch up and at Vse reduce the critical engine to idle. The airplane will immediately roll, dive and yaw. The good engine must be brought immediately to idle and then gently brought back up to reduce the decent rate but only to a power setting that will allow the airplane minimum sink while maintaining directional control.

 

 

The second major complexity with multiengine aircraft is never even discussed, probably because the people that have it happen to them die.

This happens when the door pops open on takeoff. Because the engine is to the side of the door, the door will pop open about 12 to 18 inches. This destroys the lift over the wing root by disrupting the air flow over the wing and also over the elevator and rudder. This disruption reduces the lift much more than losing an engine and also causes adverse yaw. Climb rate in my Cessna 310R with 285 hp per side is only about 50 to 100 feet per minute.

When you practice this, do it on approach to landing. You will still experience the loss of lift as well as the increased yaw, but at least you will be able to more easily control it. You will find that this is much worse than losing either engine. You will probably require all available power to complete the approach so make sure that you have sufficient altitude when you practice this and do it with an experienced instructor with you. You will not be able to shut the door once it opens.

These are the two most dangerous situations encountered in a multiengine aircraft. Practice them and be aware of them so that you can continue to fly safely.