The dreaded 3-engine ferry
Geeze, I'm sorry I missed this thread from the beginning. I was "on the road" as the airline pilots say--except there twern't no roads where I was.
Three engine ferrys are a fact of life. I don't have much to add except that maybe someone might find the actual documentation interesting. Here's my company's chapter on the subject.
My comments italicized in brackets.
A. General
Three engine takeoffs are permitted to move the aircraft from an airport where no maintenance is possible or practical to a maintenance base with one engine and/or propeller inoperable.
B. Takeoff Restrictions
1. Obtain a 3 engine ferry permit from maintenance and make appropriate logbook entry.
2. No revenue cargo shall be on board.
3. Only the crew necessary for flight operation will be on board the aircraft.
4. Maximum gross weight must not exceed 81,000 pounds.
5. Adjust takeoff weight to meet the requirement for runway length and elevation in accordance with enroute limitations...etc...
6. The propeller of the inoperative engine must be removed or feathered prior to takeoff.
7. Close the cowl flaps on the inoperative engine (-4 degrees).
C. Prior to takeoff
Observe the following safety precautions:
1. Adjust the seat and rudder pedals so that FULL RUDDER can be applied.
2. Complete the clean up items on the engine failure checklist.
3. The propeller of the inoperative engine must be FEATHERED or REMOVED, the IGNITION OFF, and the cowl flaps FULLY CLOSED.
4. Set the trim tabs to ZERO TRIM.
5. Extend wing flaps to the 20 degree DOWN position [Yeah like we'd extend wing flaps to the 20 degree UP position...]
6. DO NOT RAISE THE NOSE WHEEL from the ground BELOW a speed of 91 KIAS [Three engine Vmc is 83 KIAS]
D. Takeoff procedure
1. After lining up with the runway, hold the brakes and perform the 30 inch check [manifold pressure] on the three operating engines. On gravel runways, perform the 30 inch check on the roll, if runway and conditions permit. Accelerate symmetrical engines to maximum wet power. [Water injection allows greater manifold pressure]
2. As soon as the airplane is rolling (approx. 9 to 17 knots) gradually accelerate the remaining engine up to take off power.
3. Maintain directional control with the nose wheel steering. As required, apply slight down elevator to obtain greater traction of the nose wheel. (With an aft CG down elevator is required throughout the takeoff run.)
4. Apply full rudder away from the inoperative engine until a speed of 61-69 knots is reached. Decrease rudder application to the amount required to hold the airplane straight.
5. After all throttles of the operative engines are set for takeoff power, apply about 1/2 aileron toward the side with two engines operating.
6. Directional control up to 61-69 knots must be maintained by the use of nose wheel steering. From this speed to the liftoff speed, directional control is maintained by a combination of nose wheel steering and displacement of the rudder and ailerons. At the liftoff speed lift the airplane off the ground cleanly and simultaneously roll the wings down about 5 degrees away from the inoperative engine. This will decrease the amount of rudder required to hold the airplane straight.
7. Caution must be excercised whenever the operating airspeed is below the two engine out VMCa airspeed of 115 knots.
8. If obstacle clearance is required, climb at V2 speed. When obstacles are cleared make the transition to enroute climb configuration and speed.
--So there you have it. Now you know how to takeoff a DC6 with three engines.
Obviously the most critical time during the entire manuever is when you're accelerating between the three-engine Vmc (83 knots) and the two-engine Vmc (115 knots).
An additional engine failure (on the same side) between these two speeds would ruin your whole day.
As for the procedure itself, it takes some teamwork and a really good briefing.
The FE (per the Book) will advance the symmetrical engines. The Capt will steer with the tiller and rudder and "feed in" the remaining engine as the rudder gains effectiveness. The FO will keep ailerons deflected into the good engines until the Capt releases the tiller and steers with the yoke. When the Capt is flying the plane with aileron and rudder and elevator he'll "give" the remaining engine to the FE and it's pretty much a three engine flight from there.
It really is no big deal *except* for that short time between 3-eng Vmc and 2-eng Vmc.
Not to mention contaminated runways...and skipping nosewheels.