DROGUE SEVERANCE CUTTER
The Drogue Severance Cutter (also referred to as FLSC Holder Assembly) is a specialized product incorporating an electric detonator initiating a small length of FLSC. The Drogue Cutter is utilized on the ACES II Ejection Seat installed in the F-15, F-16, B-1B, B-2, F/A-22, F-117 and A-10. This same cutter will be incorporated to the ACES V once fielded. There are two cutters per seat and utilized to sever the Drogue Parachute Riser Assembly during the ejection sequence and prior to the deployment of the Personal Recovery Parachute. The cutters use FLSC to sever the risers. The FLSC is initiated by a dual bridgewire detonator charge incorporated in the assembly and is electrically fired.
Function of the cutters occurs once the seat has cleared the aircraft during ejection. A drogue parachute is deployed from the seat to stabilize and slow it in flight. After slowing, the two Drogue Severance Cutters fired at approximately the same time receiving their signal for an electronic sequencing unit and power from capacitor charged by a Thermal Batter. Upon activation, the FLSC severs the applicable drogue parachute bridle which releases the drogue parachute from the seat. This event occurs before deployment of the Aircrew Recovery Parachute, preventing entanglement.
Mounting on the ACES II Seat is accomplished by installing it in a cavity so that it faces the drogue bridle that it will sever. The cutter is held in place with a single high torque bolt through a slot at the ‘top’ of the cutter (right side in illustration below. This slot design provides proper mounting and alignment of the cutter in relation to the drogue bridle.
The cutters were qualified to Boeing (McDonnell Douglas) specification A114302-511. The detonator design is qualified to MIL-I-23659. It mates with a Bendix PC06-8-4SW connector or equivalent.
–65°F to +200°F
1×10-5 cc/sec. Helium
Recommended All-Fire Current
3.5 Amps minimum
Function Time (at 3.5 Amp Minimum)
10 milliseconds maximum.
1+ 0.1 Ohms.
25,000 volts discharged from a 500 Pico farad capacitor between shorted pins-to-case through a 5,000 ohm resistor in series
Complete severance of riser material, per Mil-W-27657 Type V, Nylon Webbing plus 1 thickness of Mil-T-43566 Type 1, Class 4 Cotton Tape
MIL-STD-810 Method 510, Except High Temperature 200°F. Dust concentration was .3 grains / ft., velocity was 1,750 feet/minute for a duration of 28 hours. All units fire successfully.
MIL-C-83124 paragraph 188.8.131.52: Temperature –65°F & stabilized, then placed in 100°F/90% relative humidity until ice disappears, then –65°F & stabilized, then fired at –65°F
Submerged in 2 inches of water with gap completely filled with water. Fired successfully.
6 Foot Drop
Dropped Firing Mechanism Up, Firing Mechanism Down and Side, then fired units successfully.
IAW MIL-STD-331A, Test 103.1 Procedure 1 Dropped Firing Mechanism Up, Firing Mechanism Down and Side. Units did not fire and were safe to dispose of.
Platform Use & Heritage
AV-8B, JAS-39, T-38A/N, T-6, Concept Aircraft
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