Some elements of a before-landing checklist are universal. Seat belts? Fastened. Mixture? Rich. Landing light? On.
But what about the auxiliary fuel pump? On or off? The answer depends on the airplane, and a quick check of the pilot’s operating handbook (POH) should tell us what we need to know. Of course, we could ignore the POH and just follow our instincts—but that’s a sure way to get into trouble.
On March 22, 2005, a Cessna 210 was substantially damaged when it struck a fence during a forced landing just short of the runway at Sky Ranch At Carefree Airport in Carefree, Ariz. The pilot and four passengers were injured.
The flight departed Show Low, Ariz., at 12:30 p.m. with approximately 55 gallons of fuel on board. About one hour and 15 minutes later, the pilot approached Carefree. He maneuvered around a nearby mountain, entered the traffic pattern, turned base leg beyond a noise-sensitive residential area, and flew an extended base to final.
According to the pilot, on short final with the landing gear down and full flaps, the airplane began settling. He added power, but the engine failed to respond. The airplane hit the ground short of the runway about 1:50 p.m.
A post-accident examination found no problems with the engine. The pilot told FAA inspectors that it was his habit to use the fuel boost pump for landing, even though the POH did not call for it.
According to the “Airplane and System Descriptions” section of the aircraft’s POH, “If the engine-driven fuel pump is functioning and the auxiliary fuel pump switch is placed in the ON position, an excessively rich fuel/air ratio is produced unless the mixture is leaned.”
Moreover, the Cessna “Pilot Safety and Warning Supplements” booklet states the following with regard to normal auxiliary fuel pump operation: “During cruise, the auxiliary fuel pump(s) may be used at any time to clear excessive fuel vapor, as evidenced by an unstable fuel flow indication; however, the auxiliary fuel pump(s) should be turned off prior to descent. Failure to turn off the pump(s) could cause a power failure at reduced throttle settings or with a rapid throttle advance due to an excessively rich mixture.”
NTSB investigators determined that the probable cause of the accident was the pilot’s improper use of the fuel boost pump contrary to procedures specified in the aircraft’s POH and other documents. When the throttle was advanced rapidly during the reduced-power approach with the fuel pump on, the engine became flooded.
Fuel pump configuration and use varies from one airplane model to another, and sometimes within a model. Some designs (particularly low-wing aircraft) require the boost pump to be on for landing and takeoff. In other designs (typically high-wing aircraft like the accident airplane), the boost pump is used only for high-altitude operation or when the mechanical pump fails.
As pilots, it’s important for us to be familiar with fuel pump operation for each airplane we fly, as well as other systems unique to our aircraft as outlined in the POH. Spending some time with this important manual—and following the procedures in it—will help ensure that we don’t reunite with terra firma sooner than planned.
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