FAA Aviation Mechanic Airframe (AMA)Fuel, Cabin and Ice Control SystemsHard
A regional jet is forced to attempt an emergency landing shortly after takeoff at a weight well above its maximum structural landing weight. The aircraft is equipped with a fuel jettison system. What is the primary purpose of activating this system before landing?
- ATo balance fuel quantity symmetrically between left and right wing tanks
- BTo reduce aircraft weight to at or below the maximum landing weight to reduce structural loads and improve stopping performance
- CTo prevent fuel from freezing during a rapid descent
- DTo purge air from the fuel lines prior to engine shutdown
Show answer & explanationAnswer & explanation
Correct answer: B. To reduce aircraft weight to at or below the maximum landing weight to reduce structural loads and improve stopping performance
Fuel jettison systems allow rapid dumping of fuel overboard so an aircraft that must land shortly after takeoff can reduce its weight down to or near maximum landing weight, reducing landing gear and structural loads and improving stopping performance.
Why the other options are wrong
- A. Lateral fuel balancing is handled by transfer systems, not jettison.
- C. Fuel freezing is unrelated to the jettison system's emergency purpose.
- D. Purging air from fuel lines is unrelated to jettison system operation.
Fuel Jettison System
A system on some transport aircraft that allows rapid dumping of fuel overboard in flight to reduce aircraft weight to at or below maximum landing weight for an emergency return landing.
- Required on aircraft where max takeoff weight substantially exceeds max landing weight
- Fuel is dumped through wingtip or trailing edge nozzles
- System typically retains a minimum reserve fuel quantity even after full jettison
Memory trick: Jettison sheds fuel weight fast for a safe heavy landing.