CHAPTER 3 MK 7 AIRCRAFT RECOVERY EQUIPMENT

CHAPTER 3 MK 7 AIRCRAFT RECOVERY EQUIPMENT Present-day aircraft normally require the use of runways that are 5,000 to 8,000 feet long in order to land ashore. On an aircraft carrier, these same aircraft are stopped within 350 feet after contacting the deck. This feat is accomplished through the use of aircraft recovery equipment, including an emergency barricade that brings a landing aircraft to a controlled stop by absorbing and dispelling the energy developed by the landing aircraft. This recovery equipment is commonly called arresting gear. The sole purpose of an aircraft carrier is to provide a means of launching a strike against an enemy anywhere in the world. After the aircraft complete their mission, the carrier must provide a means of safely recovering them. The Mk 7 arresting gear provides this means. AIRCRAFT RECOVERY LEARNING OBJECTIVE: Describe aircraft arrestments aboard aircraft carriers. Describe prerecovery preparations. Describe normal aircraft recovery operations. Describe emergency aircraft recovery operations. Aircraft arrestments aboard carriers are classified as either a normal arrestment or an emergency arrestment. Simply stated, arrestment is accomplished in the following manner: the arresting hook of the incoming aircraft engages a wire rope cable, called a deck pendant, that spans the flight deck in the landing area. The force of the forward motion of the aircraft is transferred to purchase cables that are reeved around a movable crosshead of sheaves and a fixed sheave assembly of the arresting engine (see fig. 3-1). The movable crosshead is moved toward the fixed sheave assembly as the aircraft pulls the purchase cables off the arresting engine, forcing a ram into the cylinder holding pressurized hydraulic fluid (ethylene glycol). This fluid is forced out of the cylinder through a control valve that meters the flow to an accumulator until the aircraft is brought to a smooth, controlled arrested landing (see fig. 3-2). After arrestment, the aircraft's arresting hook is disengaged from the deck pendant. A retract valve is then opened, allowing fluid to be forced from the accumulator back into the engine cylinder, forcing the ram out. As the ram moves out of the cylinder, the crosshead is forced away from the fixed sheave assembly, pulling the purchase cables back onto the engine until the crosshead is returned to its BATTERY position and the crossdeck pendant is in its normal position on the flight deck. PRERECOVERY PREPARATIONS Prior to recovery of aircraft, all recovery equipment and landing area must be made ready and all personnel properly positioned. The following is a general listing of the events that must be accomplished prior to the recovery of aircraft: � All operational retractable sheaves raised to the full up position � All aft deckedge antennas positioned, as required � Ready barricade, including deck ramps, in a ready status with a clear route to the landing area and a tractor with driver standing by � All launching accessories clear of the landing area � Appropriate catapult shuttle(s) (as applicable) are aft with the grab latch disengaged and the shuttle spreader cover installed � The catapult centerdeck hatch and any other hatches in the waist catapult area closed and dogged down � Jet Blast Deflectors (JBDs) completely lowered and hydraulics secured � Waist catapult safety light in the down position, if applicable � Catapult #3 track slot buttons installed � Waist catapult Integrated Catapult Control Station (ICCS) fully lowered, if applicable 3-1