PS Magazine - TB 43-PS-621
PS, The Preventative Maintenance Monthly
ISSUE 621
AUGUST 2004
UH-60A/L/Q…
Part
AN4-12A
AN4-13A
AN4-14A
AN4-15A
AN4-16A
AN4-17A
AN4-20A
AN4-21A
AN4-22A
AN4-23A
AN4-24A
AN4-25A
AN4-26A
AN4-27A
AN4-30A
AN4-31A
AN960C416
NAS1149D0463K
M220365-428
224409-013
NSN
Item
Bolt
Bolt
Bolt
Bolt
Bolt
Bolt
Bolt
Bolt
Bolt
Bolt
Bolt
Bolt
Bolt
Bolt
Bolt
Bolt
Washer
Washer
Nut
Washer
Always verify weight with gram scale
Use
appropriate
bolt length
shown plus
number
of washers
shown to
obtain the
amount
of grams
indicated.
Weights
shown
include nut.
4
5
3
4
2
3
2
4
5
3
5
2
3
2
5
2
4
3
2
3
2
4
2
3
4
2
3
2
5
2
3
4
2
3
2
5
2
3
2
2
3
2
1
1
1
1
1
1
2
3
1
1
2
1
1
2
1
1
2
1
4
1
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
12
12
13
13
14
14
15
14
14
15
15
16
16
17
16
17
17
17
18
18
19
18
19
19
19
20
20
21
20
21
21
21
21
22
23
22
23
23
23
24
24
25
SS4409-013
AN960C416
NAS1149D0463K
Grams
AN4-22A
AN4-23A
AN4-24A
AN4-25A
AN4-24A
AN4-25A
AN4-26A
AN4-27A
AN4-30A
AN4-27A
5
2
3
4
2
3
2
5
2
3
2
2
1
1
2
1
1
103
104
105
106
107
108
109
110
111
112
113
24
25
25
25
26
26
27
26
27
27
28
SS4409-013
AN960C416
NAS1149D0463K
Grams
AN4-30A
AN4-31A
2
2
3
2
4
2
3
7
2
3
6
2
5
3
4
2
6
3
2
2
3
6
2
3
2
5
2
4
2
5
6
2
2
3
5
2
3
2
3
5
2
4
2
3
2
1
1
2
1
1
1
1
1
2
1
1
1
2
1
1
2
1
1
1
3
2
2
1
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1
1
1
2
2
1
3
2
3
3
4
3
4
5
5
5
4
6
6
7
6
7
7
8
7
7
9
9
9
9
10
10
10
10
10
11
11
12
12
13
SS4409-013
AN960C416
NAS1149D0463K
Grams
AN4-12A
AN4-13A
AN4-14A
AN4-15A
AN4-15A
AN4-14A
AN4-15A
AN4-17A
AN4-16A
AN4-17A
AN4-20A
AN4-14A
AN4-15A
AN4-16A
AN4-16A
AN4-17A
AN4-20A
AN4-21A
Dear SGT Williams,
Good job. Looks like you’ve solved a weighty
situation with this tail rotor balance chart.
PS 621
36
this chart is a
life-saver when
correcting tail
rotor balance!
Dear Rotor,
Correcting tail rotor balance on our Black
Hawk is a tedious maintenance procedure.
It requires having the right hardware
stack-up of bolts, washers, and nuts for
each quadrant and use of a gram scale for
ensuring the required weight and balance.
We’ve come up with a handy tail rotor
balance weight chart that tells you the
hardware needed for a given weight needed
to correct tail rotor balance. We use the
chart in conjunction with procedure 5, Page
0069 00-25 listed in TM 1-6625-724-
13&P and the corresponding parts list in Fig
75 of TM 1-1520-237-23P-2.
The chart is used like so: Find the weight
needed in the right column, then move to
the left to determine the number of washers
and the correct bolt to use.
The chart allows for the thickness of the
retention plate, so that for each weight
shown, we have the correct amount of the
threads on the end of the bolts.
The weight listed is approximate. So you’ll
need to verify the hardware weight with a
gram scale.
SGT Steven Williams
AASF, INARNG
621. 36-37 (C)
7/7/04
10:51 AM
Page 1
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