GB2228458A

GB2228458A - Flight data recorder ejector

Info

Publication number: GB2228458A
Application number: GB8904215A
Authority: GB
Inventors: Eric David Whybray
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-02-24
Filing date: 1989-02-24
Publication date: 1990-08-29
Also published as: GB8904215D0

Abstract

The Flight Data Recorder 9 is mounted on a propellant unit 14. During a catastrophic crash the crash detection unit 15 responds to temperature, water pressure and/or impact forces generated and at a predetermined level releases a spring loaded firing pin to fire a gas cartridge with the resultant pressure being transferred to a piston 16 at the base of the launch unit 17. Movement of the piston unlatches hold-down clamps restraining the propellant unit and fires the propellant which ejects the recorder clear of the aircraft wreckage, through a frangible panel 10. <IMAGE>

Description

FLIGHT DATA RECORDER EJECTOR This invention relates toan automatically operated Flight Data Recorder Ejector.

A Flight Data Recorder is the accepted method of storing continuously,data relevant to an aircraft's systems performance and related flight conditions,ie height,speed and attitude, and to which in the event of a crash,accident investigators refer in their efforts to determine the cause of the crash. Whilst a Flight Data Recorder is designed and constructed to resist the destructive forces of a major aircraft crash, recovery of the recorder is frequently delayed or made impossible by the severity of the crash,the nature of the terrain or loss in deep water.

By ejecting the recorder clear of the aircraft at the moment of impact,recovery will thereby be rendered more easy.

According to this invention there is provided for aircraft installation and to operate automatically a Flight Data Recorder Ejector comprising of three integrated units, the crash detection unit, the launch unit and the propellant unit. The crash detection unit by means of the expansion and contraction of capsules together with the motion of an inertial mass,detects the excursions of temperature,water pressure and or impact forces attendant on an aircraft crash; and which,when thepreset ejection level is exceededsinitiates the recorder ejection sequence by releasing a firing pin to strike the firing cap of a gas pressure generating cartridge.

Coupled to the crash detector unit by a pressure transfer pipeline is the launch unit incorporating a piston actuated latch release and firing pin,activation of which by gas pressure from the crash detection unit unlatches the holddown clamps securing the propellant unit and fires the propellant charge,burning of which generates pressure to eject the assembly of propellant unit ,retrieval pack housing and flight data recorder from the launch tube and through the frangible panel provided in the skin of the aircraft,with continuing burn of the propellant carrying the assembly clear of the aircraft. Additionally there is provision for an alternative form of detector unit with special application to military aircraft routinely subjected to high magnitude manoeuvre induced "G" forces.

A specific smbodiment of the invention will now be described by way of example with reference to accompanying drawings in which : Figure 1 shows in cut-away perspective,location of the crash detection and launch units as installed in the rear fuselage of a transport aircraft.

Figure 2 shows a schematic arrangement of the complete ejection assemblyinstalled in the launch unit.

Figure 3 illustrates the general arrangement of the component parts of the detector unit applicable to both civil and military tranport aircraft.

Figure 4 is an end elevation of Figure 3 showing the disposition of the lateral impact detectors.

Figure 5 is a section through Figure 4 illustrating the lateral impact detector slide construction.

Figure 6 illustrates the hold-down latch release and firing mechanism of the launch unit with the propellant unit in situ.

Figure 7 illustrates the features of the alternative crash detector unit giving special application to highly manoeuvre-able military aircraft.

Referring to the drawing Figures 1 & 2 the two installed elements of the recorder ejection system the crash detection unit 15 and the launch unit 17 are mounted in the aircraft fuselage aft of any pressure bulkhead,with the launch tube 0 inclined at an angle of approximately 50 to the horizontal and with a frangible panel 10 above. The detector unit coupled to the launch unit via a short pipeline is aligned with its longitudinal axis parallel with the longitudinal axis of the aircraft. The flight data recorder 9 is located in a housing 11 beneath the frangible panel 10 and guided on ejection by rollers 12 . Space for a retrieval pack which may comprise of flotation gear,drag parachute and emergency beacon in the housing 13 .The propellant charge is housed in the propellant unit 14 with the hold-down release and firing mechanism 16 located in the base of the launch unit. Onejection the quick-break electrical connector 18 disconnects the recorder from the aircraft systems whilst the resilient mounts 19 absorb the initial shock of ejection as the propellant ignites.

Referring to the Figures 3 4 & 5 the detector unit has three sets of sensing elements,the longitudinal and lateral impact detectors,inertial masses 21 & 22, the temperature expansion capsules 25 and the water pressure compression capsules 26. With the manual safety pins 28 removed and the remotely switched arming unit 29 set to arm, application of temperature,water pressure or impact forces above a predetermined value and set by spring loading on the detent balls 17 cause the impact detector 21 to slide forward to release the firing pin 23. This pin is then driven aft under spring pressure to strike the firing cap of the cartridge 24 which ignites and the resultant gas pressure transfers by connecting pipeline to the launch unit.

Referring to Figure 6 the gas pressure from the crash detector unit enters the base of the piston chamber 30 via pipeline 33 and with the safety pin 32 removed and arming unit 31 set to arm, the piston and firing pin assembly is driven upwards, the release cone 35 forces open the propellant unit hold-down latches 36 followed by the firing pin striking the igniter cap of the propellant 38.

Ignition of the propellant established, pressure in the launch tube rises rapidly,being retained by the sealing ring 37 and referring again to Fig.2 the assembly of propellant unit 14 retrieval pack 13 and flight data recorder 9 accelerates rapidly from the launch tube 17 breaking the electrical connection 18 and shattering the frangible 10 with the sustained propellant burn then carrying the assembly clear of the aircraft wreckage.

A further example of embodiment of the invention illustrating the function of the crash detection unit which has specific application to military aircraft routinely subjected to high levels of manoeuvre induced "G" force is now described with reference to Figure 7.

To obviate need to set over-high impact trigger levels to prevent in-advertant triggering during aircraft manoeuvre,means is provided whereby induced "G" forces are nulled. Where-as construction and function of the temperature and water pressure detector elements 25 and 26 are as described with reference to Fig. 3, the lateral impact detectors are deleted and replaced by a soft iron ball 42 seated on an electromagnet 40 and connected by an articulated joint to the longitudinal impact detector 21. During flight, signals proportional to induced "G" forces are fed from the aircraft accelerometers to the DC amplifier 41 which in turn feeds a proportional electrical current to the electromagnet generating a magnetic field which attracts the ball and thereby increasing the lateral force necessary to displace the ball by an amount equivalent to that produced by the applied "G" force and thusc-anc-eIl-im~g the "G" effect. On crash landing the ball will respond to lateral impact forces by moving off its seat drawing the longitudinal detector 21 forward releasing the firing pin 23 to initiate the ejection sequence.

Claims

1 A crash activated flight data recorder ejector comprising an ejectable assembly of flight data recorder, retrieval pack housing and propellant unit, which on ejection shatters a frangible panel and travels clear of the aircraft a launch unit with means for releasably securing the ejection assembly until moment of ejection and a crash detector unit with means whereby the necessity to eject is sensed and the eject command initiated.

2 A flight data recorder ejector as claimed in claim 1 wherein the crash detector means is provided which when subjected to temperature in excess of a predetermined level, initiates the ejection of the recorder from the aircraft.

3 A flight data recorder ejector as claimed in claim 1 wherein the crash detection means is provided which when subjected to water pressure (ie depth of submersion) in excess of a predetermined level,initiates the ejection of the recorder from the aircraft.

4 A flight data recorder ejector as claimed in claim 1 wherein the crash detection means is provided which when subjected to impact forces in excess of a predetermined level, initiates the ejection of the recorder from the aircraft.

5 A flight date recorder ejector as claimed in claim 1 wherein the crash detector means for sensing the need to eject the flight data recorder as claimed in claim 2 claim 3 and claim 4 is caused to release a firing pin to strike the igniter cap of a gas pressure generating cartidge.

6 A flight data recorder ejector as claimed in claim 1 wherein the launch unit is provided with releasable propellant unit hold-down means together with propellant cartidge firing means.

7 A flight data recorder ejector as claimed in claim 1 claim 5 and claim 6 wherein the propellant unit hold down means and the propellant ignition means are activated by gas pressure from the crash detector unit.

8 A flight data recorder ejector as claimed in claim 1 wherein means is provided whereby the propellant unit, retrieval pack housing and flight data recorder assemble as one unit prior to installation of the propellant unit in the launch tube.

9 A flight data recorder ejector as claimed in claim 8 wherein guide means are provided cooperable with the ejection assembly giving initial guidance on ejection.

10 A flight data recorder ejector . as claimed in claim 1 and claim 4 wherein the crash detection means is made compatible with the flight performance of highly manoeuvre-able combat aircraft.

11 A flight data recorder ejector substantially as described herein with reference to Figures 1 - 7 of the accompanying drawing.