H28879 H28887
Main Cabin Smoke Detection System Component Location 501
26-16-0 Figure 1 (Sheet 1) Aug 15/69
Page 2
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
511 Main Cabin Smoke Detection System Component Location
May 15/69 Figure 1 (Sheet 2) 26-16-0
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BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
2. Smoke Detectors
A. The smoke detectors consist of a test lamp, a beacon light, a photoelectric cell, associated circuitry, and a smoke chamber with an inlet port and an exhaust port. The components are arranged in the chamber so that the beacon light projects a beam perpendicular to the line of sight of the photoelectric cell. When smoke is present in the chamber, light from the beacon is reflected from the smoke particles into the photoelectric cell. The photoelectric cell resistance decreases and enough current is passed to the control amplifier to operate the amplifier whenever the existence of smoke reduces the light transmission to approximately 10 percent below that of clear air. The smoke reflects light from the beacon and it is the reflective properties of smoke, not the decrease in light transmission, which is used to actuate the alarm signals. The test lamp is directly in the line of sight of the photoelectric cell. Testing the smoke detectors involves illuminating the test lamp, which simulates light reflection from smoke particles. The system then operates as if smoke were detected and operates the warning devices.
H28883
Smoke Detection System Tubing Connections 501
26-16-0 Figure 2 Aug 15/69
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BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
3. Control Amplifier
A. An A and B smoke detector is connected to each control amplifier. The control amplifier contains two transistors, a relay and associated circuitry. The two transistors amplify the signals from either the A or B smoke detectors and energize the control relay. The control relay then completes voltage to fire protection module P8-1 cargo smoke lights and alarm circuits.
4. Aural and Visual Warning Components
A. The following aural and visual warning components are used by the smoke detection system. The same components are also used by other fire protection systems. (Refer to 26-00, Fire Protection)
B. Warning Lights
(1) Two red cargo smoke lights (forward and aft) and two red master fire warning lights provide visual indication of detection of smoke by the smoke detection system. The cargo smoke lights are on fire protection module P8-1. The master fire warning lights are on pilots' lightshield P7. The lights may be pressed to test for normal operation. Pressing a master fire warning light when an alarm has sounded will also cause the master fire warning lights to go off and silence the alarm bell. The cargo smoke lights will not go off until the smoke condition and alarm signal has cleared.
C. Alarm Bell
(1) The alarm bell is operated by any of the fire protection systems. The bell is installed in the aural warning devices box adjacent to the control stand in the control cabin. (Refer to 31-26-0, Aural Warning and Call Devices)
D. Bell Cutout Switch
(1) The bell cutout switch is on fire protection module P8-1. Pressing the switch causes the bell to silence and turns off the master fire warning lights.
511
May 15/69 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 26-16-0 Page 5
H28774
Main Cabin Smoke Detection System Schematic 511
26-16-0 Figure 3 May 15/69
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BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
5. Smoke Detector Tubing
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