1. Remove Exhaust Gas Temperature Indicator
A. Open applicable circuit breakers pertaining to indicator being removed.
WARNING: TAG AND SAFETY THE CIRCUIT BREAKERS.
B. Record position of indicator (such as 9 o'clock position) with respect to rest of panel to facilitate installation.
C. Loosen indicator mounting clamp adjustment screw. (See figure 401.)
D. Remove indicator by pulling straight out of panel clamp.
E. Disconnect terminals or electrical connector from indicator.
NOTE: Tag wires to identify if terminals are used.
2. Prepare for Installation
NOTE: If indicator is being replaced with a new indicator it will be necessary to prepare for installation in accordance with steps A. and B.
A. Remove shorting strap from new indicator.
B. Install shorting strap between alumel and chromel terminals on old removed indicator.
C. Make certain applicable circuit breakers pertaining to indicator to be removed are open and tagged.
3. Install Exhaust Gas Temperature Indicator
A. Connect terminals or electrical connector to indicator.
B. Insert indicator into panel.
C. Align indicator so that 9 o'clock position is as recorded in paragraph 1.B.
D. Tighten mounting clamp adjustment screw.
E. Close circuit breakers and remove safety tags.
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May 15/68 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 77-21-41 Page 401
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Exhaust Gas Temperature Indicator Installation 500
77-21-41 Figure 401 May 15/68
Page 402
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
AIRBORNE VIBRATION MONITORING SYSTEM (CONSOLIDATED) -DESCRIPTION AND OPERATION
1. General
A. The airborne vibration monitoring system measures the amount of engine vibration, and shows the engine vibration level on indicators at the center instrument panel. If any vibration increase is stabilized for over 30 seconds, it maybe an indication of engine malfunction. Instantaneous warning of the malfunction permits corrective measures before extensive damage occurs.
B. The system basically consists of two vibration pickups and one indicator for each engine, and a monitor unit, a pickup selector switch and a test switch for the two engine system.
C. Vibration pickups generate alternating electrical signals proportional to the amount of engine vibration, and transmit the signals to the monitor unit. The monitor unit amplifies and rectifies the alternating electrical signals to pulsating dc signals, which operate the corresponding vibration indicators on the center instrument panel. A pickup selector switch is used to select the signals from either the engine inlet pickups or turbine section pickups of the two engines simultaneously. The test switch checks circuit continuity of the two engine airborne vibration monitoring system.
2. Engine Vibration Pickup
A. The engine vibration pickup is a transmitter used to convert mechanical energy of vibration to alternating electrical signals of proportional magnitude. Each pickup is enclosed in a hermetically sealed case. A stabilized, permanent magnet is suspended on springs inside a coil. The coil is attached to the cylindrical case of the pickup which, in turn, is mounted on the engine. There are two pickups for each engine; one is located approximately at the 11 o'clock position on the front flange of the engine inlet case, while the other is on the turbine case forward flange at approximately the 6 o'clock position.
B. As the engine vibrates, the case and coil move with the engine, but the magnet being suspended tends to remain at rest. The relative motion between the magnet and the coil generates alternating electrical signals in the coil, which appear as the pickup output.
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May 01/76 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 77-32-0 Page 1
3. Engine Vibration Monitor Unit
A. The engine vibration monitor unit receives signals from the engine-mounted vibration pickups and transmits the amplified signals to the indicators. The monitor unit consists of two electronic channels. Each channel contains a signal integrator, signal amplifier, and a sensitive relay. The monitor unit with its power supply is located on the electrical equipment shelf (E3) in the electronic equipment compartment.
B. The monitor unit channels integrate input signals, filter out undesired frequencies, and amplify and rectify alternating signals to pulsating dc signals. The dc signals, transmitted through sensitive relays, appear as the output signals of the monitor unit.
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