TB 1--1520--240--20--146
special inspection required by this Safety of Flight (SOF) does not zero
the 1200 hour operating time special inspection required in TM
55-1520-240-23, Task 1-92 (H-47D/F), Reference No. 21, or TM
1-1520-252-23, Task 1-100 (MH-47E), Reference No. 17.
(2) Inspect tie bar assemblies as follows --
(a) Visually inspect tie bar plates for cracks using 10X magnification. No cracks allowed.
NOTE
Surface irregularities (i.e. scratches and manufacturing defects) found
while using the 10X magnification are not grounds for rejection.
(b) Inspect the four tie bar slots using a borescope with a rigid right angle probe. Insert the
borescope probe in each slot and examine the plates for cracks along the full depth and span of the slot.
Recommend the probe not exceed 0.110 inch diameter. If a suitable borescope and probe are not avail-
able, visually inspect each slot using a light source.
NOTE
Cracks will appear perpendicular to the plate surfaces and should not be
confused with horizontal scratches or tools marks.
(c) Inspect washers for deformation (dishing) and cracks. A dished washer will have a gap
between it and the adjacent plate. The maximum separation between the washer and the adjacent plate
is 0.015 inch. No cracks allowed.
(3) If a tie bar assembly fails an inspection in accordance with paragraph 8b, correct in accor-
dance with paragraph 9.
(4) If no damage is found --
(a) Reinstall the rotary wing head tie bar assemblies in accordance with TM 55-1520-240-23,
Task 5-23.2 (H-47D/F) or TM 1-1520-252-23, Task 5-32 (MH-47E).
(b) Clear the red horizontal dash //--// entry.
9. Correction Procedures. If the TSN is equal to or more than 4800 hours, or if a tie bar assembly fails
an inspection in accordance with paragraph 8b, proceed as follows --
a. Change the rotor head DA Form 2408-16 to indicate a new retirement life for the tie bar assembly
of 4800 hours TSN.
b. Clear the red horizontal dash // -- // entry and enter a red // X // status symbol with the following state-
ment: "Replace the rotary wing head tie bar assemblies in accordance with CH-47-02-05 (TB
1-1520-240-20-146)."
c. Submit a Category I Deficiency Report on any tie bar assembly that has failed the inspection required
in accordance with paragraph 8b due to cracks.
d. If you have tie bars on hand which previously failed the inspection in accordance with CH-47-02-03
for other than cracks and/or deformed washers, refer to paragraph 10d for disposition instructions.
e. If TSN is equal to or more than 4800 hours, contact the technical point of contact in paragraph 16a
for diaposition instructions.
NOTE
Ensure that replacement tie bar assemblies are inspected and in com-
pliance with this Safety of Flight (SOF) prior to installation.
f. Replace the rotary wing head tie bar assemblies in accordance with TM 55-1520-240-23, Task
5-23.2 (all H-47D/F) or TM 1-1520-252-23, Task 5-32 (MH-47E).
g. Clear the red // X // entry from paragraph 9b.
4
Previous Page
