Accessory Housing Maintenance; Accessory Housing Removal - Lycoming IO-390-D Series Maintenance Manual

IO-390-D Series Engine Maintenance Manual
IO-390-D Series Engine Maintenance Manual
NOTICE: IO-390-D Series engines can be equipped with aluminum or magnesium accessory
housing. Be aware of the type of components installed on your engine before cleaning,
completing maintenance, or replacing parts.

1. Accessory Housing Removal

A. Remove any aircraft manufacturer installed accessories per instructions in the Aircraft
Manufacturer's Maintenance Manual.
B. If not already done, drain the oil from the oil sump per the "Oil Change Procedure" in
Chapter 12-10.
C. Remove the fuel pump per instructions in Chapter 73-10 of this manual.
D. Remove the oil filter (if installed) per instructions in Chapter 12-10.
E. Disconnect the hoses to the airframe-supplied oil cooler.
F. On engines with a rear-mounted propeller governor drive, remove the propeller gear drive
adapter assembly per the "Propeller Governor Drive Removal" procedure in Chapter 72-60.
G. Remove any other accessories on the accessory housing per airframe manufacturer's
instructions.
NOTICE: There are three different bolts used on the accessory housing. Identify and keep the
bolts separate for correct reassembly.
H. Remove all of the Bolts A, B, and C, lock washers, and washers from the external side of the
accessory housing shown in Figure 1. Discard the lock washers.
Hardware on External Side of Accessory Housing
I. While one person supports the accessory housing, remove the two bolts, lock washers, and
washers from the other side of the accessory housing as shown in Figure 1. Discard the lock
washers.
J. Remove and discard the tachometer drive oil seal (Figure 2) from the accessory housing.
K. Remove the accessory housing from the engine.
L. Remove and discard the accessory housing gasket (Figure 2).
© 2020 Avco Corporation. All Rights Reserved
March 2020

72-25 - ACCESSORY HOUSING MAINTENANCE

Figure 1 Figure 2
Accessory Housing
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72-25