The following stories from the February 19, 2010, edition of AOPA ePilot were provided to AOPA members who expressed an interest in the particular subject areas. Any AOPA member can receive information tailored to their areas of interest by updating their preferences online.
Categories and limits
You and your flight instructor are reviewing for your upcoming flight test. The grilling has moved to your knowledge of your trainer’s design characteristics and performance—facts such as how much usable fuel your aircraft holds, as discussed in the Feb. 12, 2010, Training Tip. Next your instructor asks you to refer to aircraft documentation and tell her the useful load of your aircraft in the utility category. Many figures are pegged in your memory for easy recall, but she just threw you a curveball. Good thing you were paying close attention to the question.
When studying your aircraft’s features, you learned that useful load of a general aviation aircraft is defined in the Pilot’s Handbook of Aeronautical Knowledge as “the weight of the pilot, copilot, passengers, baggage, usable fuel, and drainable oil. It is the basic empty weight subtracted from the maximum allowable gross weight.” (See the Nov. 17, 2006, Training Tip.)
Here’s what gives your instructor’s question its spin: There may be more than one gross weight (or ramp weight) for your aircraft. You were asked to look up the useful load in the utility category. A 1986 Cessna Skyhawk is certified in the normal and utility categories, and it must be 300 pounds lighter on the ramp to be considered in the utility category than when ramp-ready as a normal-category aircraft. Empty weight doesn’t change, so how will this affect useful load? Another restriction in the utility category—in which higher maneuver stresses may be imposed on the airframe than in the normal category—is a prohibition on rear-seat occupancy and baggage compartment loadings.
Consider the impact of those changes on the Piper Warrior III, reviewed by Mark Twombly on AOPA Flight Training Online. “Subtracting the airplane's equipped empty weight of around 1,500 pounds from the utility weight limit leaves just 520 pounds for fuel and crew. That's not a lot, so crew and fuel weight must be carefully calculated when planning a flight to include these maneuvers.”
Know your trainer’s certification and associated limitations. And always read or listen carefully to questions before responding. The correct answer may be different from the first one that comes to mind!
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Question: I was reading Final Exam last week and saw a term I was not familiar with. What is shock cooling and how can I avoid it?
Answer: Shock cooling is the rapid cooling of hot engine metals. It can stress the engine components, leading to cracks in the cylinder heads. Shock cooling most often occurs during prolonged descents at very low power settings. Pilots can avoid shock cooling their engines by planning their descents ahead of time and maintaining some power during the descent. To learn more about shock cooling and engine operations in general, read this AOPA Air Safety Foundation Safety Advisor.
Got a question for our technical services staff? E-mail firstname.lastname@example.org or call the Pilot Information Center, 800/872-2672. Don’t forget the online archive of “Final Exam” questions and answers, searchable by keyword or topic.