K80776 K80780
Flight Recorder System Simplified Schematic  504 
31-24-01  Figure 2 (Sheet 1)  Nov 15/79 
Page 4 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

577  Flight Recorder System Simplified Schematic 
Nov 15/79  Figure 2 (Sheet 2)  31-24-01 
Page 5 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

B.  After trip and date information are set up on the encoder, the encoder may be operated by pressing the REPEAT pushbutton until the amber light remains illuminated. The encoder will then begin its 15-minute recording cycle. When the flight recorder system is energized, relay K1 in the encoder becomes energized through contacts on the switch disk assembly, thus disconnecting power to the encoder motor. When the REPEAT button is pressed, relay K1 is de-energized, and the motor starts rotating a sweep arm and brush assembly across a printed circuit board (disk). When the 28 volts dc through the disk assembly to relay K1 is broken, the REPEAT button may be released. The encoder will then continue through its recording cycle until the disk contacts again complete power to relay K1 to stop the cycle. During the recording cycle, voltage is applied to the binary trip and date (reference) solenoid in the flight recorder in a sequential series corresponding to the number set up on the encoder. A thumbwheel switch set to the number 7 will then complete seven pulse marks on the recorder tape. Each number is recorded in turn until all information is recorded. The amber light will be extinguished when the recording cycle has stopped. The encoder uses 115 volts ac and 28 volts dc obtained from the flight recorder.
4.  Accelerometer (Fig. 2)
A.  The accelerometer is a self-contained sealed unit mounted on the aft side of the forward wall of the left wheel well and is accessible through the left wheel well. The accelerometer sensitive axis is oriented to detect vertical acceleration forces within a range of minus 3G to plus 6G. The unit supplies the recorder with a 400-Hz amplitude modulated signal which is a function of vertical acceleration of the aircraft. A 26-volt, 400-Hz ac excitation voltage is provided to the accelerometer from the power supply in the flight recorder.
5.  Flight Recorder (Fig. 2)
A.  The flight recorder provides a permanent record of airplane headings of 0 to 360 degrees, airspeeds of 100 to 450 knots, altitudes of -1000 to +50,000 feet, vertical accelerations of -3G to +6G, and HF or VHF radio transmission by scribing marks on a metal foil tape. Trip and date information may also be recorded. A replaceable magazine assembly contains the tape and spool assemblies.
B.  The recorder assembly consists of separate mechanical chassis and electronic assembly units. The mechanical chassis provides for installation of a magazine assembly through a hinged door in the front plate assembly. In addition, it includes the timing and actuating motor and its associated gear train, the timing and escapement mechanisms, the accelerometer commutator, the take-up servomotor and its associated gear train, the heading servo assembly, the vertical acceleration servo assembly, the altitude sensor and airspeed sensor assemblies, solenoid actuated scribes, a time remaining indicator, and magazine engagement devices. The electronic chassis includes the power interlock relay, the power supply, the precision frequency generator, heading and accelerometer servo-amplifiers, tape moving indicator and associated wiring.
504 
31-24-01 Page 6  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Nov 15/79 

C.  The magazine assembly contains the recording medium (5-inch metal foil tape), its supply and takeup spools, rollers which support and control the movement of the tape, a handle locking mechanism which locks the magazine in the recorder assembly and various recorder engagement devices. The magazine is designed to facilitate removal and replacement of the recording tape and its spools in a minimum amount of time and without damage. When installed in the recorder, the magazine is precisely positioned to prevent the need for individual adjustments each time the magazine is changed. The magazines are interchangeable between recorders. The metal foil tape is made of stainless steel and nickel thus providing high resistance to mechanical damage, heat and corrosion. The tape is driven at a constant speed of 6 inches per hour through sprocket holes in the tape is sufficient for 600 hours of recording time, 300 hours on each side. The tape spools must be reversed and rethreaded through the magazine to record on the unused side. Since the tape moves at a constant speed, an accurate time base is provided; however, timing marks are spaced at 1- and 15-minute intervals to aid in interpreting the recorded information. A lever on the supply spool senses the radius of the tape remaining on the supply spool and transmits the indication through a linkage to the tape remaining indicator mounted immediately behind the door. A potentiometer mechanically connected to the linkage transmits an electrical signal to the tape remaining indicator on the encoder panel. The encoder indicator is calibrated in hours; the recorder indicator is calibrated in feet.
　
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