Stud Replacement - Lycoming IO-390-D Series Maintenance Manual

IO-390-D Series Engine Maintenance Manual
IO-390-D Series Engine Maintenance Manual

Stud Replacement

NOTICE: This procedure applies to crankcase, accessory housing, and oil sump studs and does not
apply to crankcase thru-studs.
The procedure for replacement of studs depends on the type of stud and how it was
damaged.
1. Replace all studs that are bent, broken, damaged, loose, rusted, corroded, or cannot be
cleaned.
2. To remove and replace a damaged stud (Figure A-1):
Figure A-1
Damaged Studs
A. If the stud has sufficient thread area, use a Stud Removal Tool (Figure A-2). Refer to the
tool manufacturer's instructions.
B. If you cannot use a Stud Removal Tool or if the stud is broken beneath the surface:
(1) Drill a small hole in the stud.
(2) Use a pilot bushing to guide the drill into the center of the stud.
(3) Drill again to adjust the size of the hole to the necessary extractor.
(4) Remove the stud with the extractor.
C. After stud removal, examine the size and condition of the threads in the stud holes. If the
stud holes are stripped or galled, replace the component or contact Lycoming Engines'
Technical Support.
D. If necessary, replace the regular size studs with oversize studs.
E. Apply a layer Loctite
stud.
F. Drive the new stud to the correct depth with an applicable stud driver. Refer to the
minimum drive torque in the latest revision of the Service Table of Limits - SSP-1776.
© 2020 Avco Corporation. All Rights Reserved
March 2020
APPENDIX A
®
Food-Grade Anti-Seize or equivalent to the threads on the new
Figure A-2
Stud Removal Tool
Appendix A
Page 293