SERVICE LETTER
Engine – Fan Rotor – Revision to Line Maintenance Manual
1. Planning Information
A. Effectivity:
This document applies to the following Williams International turbofan engines:
ENGINE MODEL ENGINE PART ENGINE SERIAL
NUMBER NUMBER NUMBERS
FJ44-1A 45700-104 ALL
FJ44-1AP 72100-200 ALL
FJ44-1AP 72100-201 ALL
FJ44-2A 56000 ALL
FJ44-2A 56000-103 ALL
FJ44-2A 56000-104 ALL
FJ44-2C 60500 ALL
FJ44-2C 60500-103 ALL
FJ44-3A 67000-200 ALL
FJ44-3A 67000-202 ALL
FJ44-3A-24 75000-200 ALL
FJ44-3AP 111000-202 ALL
FJ44-4A 73200-200 ALL
FJ44-4A-32 127000-200 ALL
FJ44-4A-QPM 73200-201 ALL
FJ44-4M 135000 ALL
FJ44-4M-34 136000 ALL
FJ33-5A 79400-201 ALL
FJ33-5A 79400-205 ALL
B. Reason:
To revise the fan rotor visual inspection (72-31-20 P.B. 601) and the fan rotor blend
repair (72-31-20 P.B 801), prior to being incorporated into the applicable Line
Maintenance Manuals.
C. Compliance:
Not Applicable.
D. Coverage:
Not Applicable.
PROPRIETARY INFORMATION
All information and technical data disclosed herein are the property of Williams International and are not to be duplicated or
disclosed to others for any purpose without the written consent of Williams International, Pontiac, MI.
Original Release Date – Mar. 23/20 WISL-72-1128
Page 1 of 5
SERVICE LETTER
E. Description:
This service document modifies 72-31-20 P.B. 601 and P.B 801 of the applicable
Line Maintenance Manuals.
F. Approval:
The technical content of this service document is FAA approved as applicable to the
engine models and serial numbers identified. It is the aircraft owner/operator
responsibility to coordinate with the appropriate aviation authority overseeing the
aircraft maintenance and operations, as required, prior to flight.
G. Manpower:
Not Applicable.
H. Material:
Not Applicable.
I. Tooling Required:
Not Applicable.
J. Weight and Balance:
Not Applicable.
K. Electrical Load Data:
Not Applicable.
L. Software Configuration:
Not Applicable.
M. References:
FJ44-1A Line Maintenance Manual.
FJ44-1AP Line Maintenance Manual.
FJ44-2A Line Maintenance Manual.
FJ44-2C Line Maintenance Manual.
FJ44-3A/3A-24 Line Maintenance Manual.
FJ44-3A (67000-202) Line Maintenance Manual.
FJ44-3AP Line Maintenance Manual.
PROPRIETARY INFORMATION
All information and technical data disclosed herein are the property of Williams International and are not to be duplicated or
disclosed to others for any purpose without the written consent of Williams International, Pontiac, MI.
Original Release Date – Mar. 23/20 WISL-72-1128
Page 2 of 5
SERVICE LETTER
FJ44-4A/4A-32 Line Maintenance Manual.
FJ44-4A-QPM Line Maintenance Manual.
FJ44-4M Line Maintenance Manual.
FJ44-4M-34 Line Maintenance Manual.
FJ33-5A Line Maintenance Manual.
N. Other Publications Affected:
Not Applicable.
O. Family Tree Charts of Modification Relationships:
Not Applicable.
PROPRIETARY INFORMATION
All information and technical data disclosed herein are the property of Williams International and are not to be duplicated or
disclosed to others for any purpose without the written consent of Williams International, Pontiac, MI.
Original Release Date – Mar. 23/20 WISL-72-1128
Page 3 of 5
SERVICE LETTER
2. Accomplishment Instructions – 72-31-20 P.B. 601
B. Visually inspect the fan blades for damage as follows (Figure 801 – Fan Blade Edge
Blending – Inspection Zones):
1) Inspect the blade leading edges (Zones B, C, and D) for:
a. Dents or nicks within limits of repair. Repair, refer to 72-31-20,
P.B. 901
b. Dents or nicks greater than limits of repair. Reject
c. Bend on blade tip. Reject
2) Minor erosion on blade leading edges Polish smooth using 120-
evidenced by rough leading edges (minute grit aluminum oxide cloth to
serrations) and multiple small shallow pits remove any roughness on
closely grouped. the leading edge, working
up to a final polish using
600-grit, with minimum
material removal. No
blending allowed.
NOTE: The rest of the procedure remains unchanged.
PROPRIETARY INFORMATION
All information and technical data disclosed herein are the property of Williams International and are not to be duplicated or
disclosed to others for any purpose without the written consent of Williams International, Pontiac, MI.
Original Release Date – Mar. 23/20 WISL-72-1128
Page 4 of 5
SERVICE LETTER
3. Accomplishment Instructions – 72-31-20 P.B. 601
A. Repair the Fan Rotor
3) Blend Limits:
ZONE MAX BLANDABLE DAMAGE SIZE ALLOWABLE EXTENT OF BLEND
No damage allowed. If there is a minor No blending allowed. After polishing, only
A scratch (<0.001 inch deep), polish to visual inspection is required. Penetrant
remove scratch. inspection and balancing is not required.
NOTE: The rest of the procedure remains unchanged.
PROPRIETARY INFORMATION
All information and technical data disclosed herein are the property of Williams International and are not to be duplicated or
disclosed to others for any purpose without the written consent of Williams International, Pontiac, MI.
Original Release Date – Mar. 23/20 WISL-72-1128
Page 5 of 5
