Page 33 - Volume 17 Number 10

sfeed?What Aboutsby Thomas P. TurnerLook at your typical multiengine airplane’s fuel panel and you’ll see a feature unique to this class of aircraft: the fuel crossfeed position. Sometime, back when you earned your multiengine rating or took your most-recent certificate or rating checkride, you may have been required to explain and/or demonstrate the operation of the fuel crossfeed system. Then again, maybe not. The fuel crossfeed system is not specifically called out in the FAA Practical Test Standards. In the rush to prepare for an initial multiengine rating, you may well have not reviewed or practiced use of the crossfeed system at all—unfortunately, most training is aimed at meeting the minimum requirements for the Practical Test, with actual mastery of the aircraft and systems sometimes taking a back seat.So, what about crossfeed? How do you use the crossfeed system? More importantly, why and when would you use it?What it isFuel crossfeed is a system that permits burning fuel in one engine from a tank on the other side of the airplane. The purpose of crossfeed is to extend range during one engine inoperative flight. A secondary function of crossfeed is to balance the fuel load when flying for long periods on a single engine.According to the FAA’s Airplane Flying Handbook, crossfeed mode is “an emergency procedure used to extend airplane range and endurance in OEI (one engine inoperative) flight. There are a few models (of multiengine aircraft) that permit crossfeed as a normal, fuel-balancing technique in normal operation, but these (types) are not common. The AFM/POH (Approved Flight Manual or Pilot’s Operating Handbook) will describe crossfeed limitations and procedures, which vary significantly among multiengine airplanes.”How do you use crossfeed?Configuring your airplane to operate in crossfeed is a simple and straightforward process. Crossfeed may be an “emergency procedure” according to the Airplane Flying Handbook, but entering and exiting crossfeed is not an emergency operation unto itself. In other words, you have plenty to time to configure for crossfeed. Pull out the AFM/POH and locate the Entering Crossfeed checklist in the Emergency Procedures section. Read through the checklist once or twice to review your actions, then read-a-step, do-a-step your way through the procedure.One typical crossfeed checklist is this one that applies to the Beechcraft King Air C90A:Boost pumps .............................................................ON Transfer pumps .................................................... AUTO Crossfeed switch ................................. OPEN (Light on) Boost pump (receiving side) ................................... OFF Fuel pressure light (receiving side) .... EXTINGUISHEDObserve the limitations of fuel crossfeed. Some models prohibit crossfeed except when one engine is shut down—no crossfeed operations “for the fun of it.” In every multiengine aircraft I know, the crossfeed system is limited to emergency use in straight-and-level flight only. So, you must exit crossfeed before beginning your descent to land. Again, it’s not an emergency... reference the checklist, read it through once or twice as a refresher, and then work step-by-step through the process. Some AFM/POHs do not provide a checklist for exiting crossfeed. If yours does not, use the Entering Crossfeed checklist, adjusting steps as makes sense to move from crossfeed to normal fuel system operation. This takes some thought, so pull out your airplane’sOCTOBER 2013TWIN & TURBINE • 31