a. Inspect the main rotor head assembly to identify the part number located on the data plate (silver
color) on the #1 hub arm. If the data plate is missing, check records for hub assembly part number and verify
(1) If the hub assembly is identified as either part number 70103-08112-047/ -048/ -049/ -050
(new production hubs), or it has been re-identified to part number 70070-10046-055/ -056, no modification
is required and the inspection is complete and the red horizontal dash / / - / / entry will be cleared.
(2) If a part number other than those listed in paragraph 8.a.(1) is installed, proceed to paragraph
b. Conduct a records/visual inspection of the hub for the following;
(1) Determine the time remaining until retirement of the hub. Only hubs with more than 1000
hours are eligible for rework.
(2) Determine if an impression stamp "RS-033-2K" is in the data block of the data plate indicating
a damper bore has been reworked. If the stamp is not present, or if the data plate is missing, the hub will
remain a candidate for rework.
(3) Determine if an impression stamp "RS70100-33G-5" or "RS-033-3H" is in the data block (un-
painted area) of the data plate. If the stamp is present, or if the data plate is missing, conduct the following
inspection for an oversized bolt hole at the 11 O'Clock position.
(a) Remove the damper brackets from all four hub arms per normal TM procedure.
(b) Inspect each of the four 11 O'Clock position bolt holes for an over size insert by measur-
ing the diameter of the chamfer (at the hub surface, not at bonded liner surface).
(c) If chamfer diameter measures greater than 0.530 inch, an oversize insert is installed and
the hub is not eligible for the modification.
c. If the hub does not meet one or more of the criteria in paragraph 8.b., the hub is not eligible for re-
d. If it is determined the hub is a candidate for rework proceed to paragraph 9.a..
e. For hubs eligible for rework:
(1) Report the initial inspection results IAW paragraph 14.a.(2).
(2) Clear the red horizontal dash / / - / / entry required IAW paragraph 1.a. of this TB . Enter a
new red horizontal dash / / - / / status symbol with the following statement; "Inspect main rotor hub IAW para
TB 1--1520--237-20-237 prior
to or during the next PMS
2, but NLT
30 September, 2004."
(3) When the aircraft is undergoing PMS 2 inspection, or other extensive maintenance which will
allow replacement of the hub, contact the LOG point of contact in paragraph 16.b..
f. Following coordination with the LOG POC in paragraph 16.b., perform the following prior to or dur-
ing the next PMS 2:
(1) Remove the hub assembly from the main rotor head assembly IAW normal procedures. Re-
move all sub--components and hardware from the hub IAW normal procedures. All serviceable hardware and
sub-components shall be retained for reinstallation per existing maintenance procedures.
(2) Clean IAW TM 1-1520-237-23-1, paragraph 1-4-7(f)(g) or TM 1-1520-250-23-1, paragraph
1.39.6, all internal/external surfaces of the hub being turned in to remove any oil, grease, and/or engine soot
(3) Inspect all four zones of the hub for cracks IAW TM 1-1520-237-23-3, paragraph 5-4-2 or TM
1-1520-237-23-3, paragraph 5.2.1, and TB 1-1520-237-20-235. If any cracks are found, the hub is not eligible
for rework. Dispose of hub IAW paragraph 10.d.(2).