MIL-PRF-28776F
TABLE IV. Sampling plan for maintenance of FR level qualification
(60 percent confidence level).
FR
Qualified FR
Maximum
Cumulative unit cycles in millions
level
(%/10,000
qualification
symbol
cycles)
maintenance
C 1/ = 1
C=2
C=3
C=4
C=5
period
L
3.0
6 months
.673
1.03
1.39
1.75
2.10
M
1.0
6 months
2.02
3.10
4.18
5.25
6.30
P
0.1
12 months
20.2
31.0
41.8
52.5
63.0
R
0.01
24 months
202
310
418
525
630
1/ C = Acceptance number or number of failures permitted. C numbers greater than five shall be
coordinated and approved by the qualifying activity.
4.6.3 Exemption of data. Exemptions of data requirement in MIL-STD-690 shall apply.
4.6.4 Qualification approval for higher FR. Qualification approval granted for one of the lower FR levels will
include qualification for all of the higher FR levels; e.g., qualification approval for level "R" will include qualification
approval for levels "P", "M", and "L".
4.7 In-process and conformance inspection.
4.7.1 In-process inspection (see 3.6).
4.7.1.1 Diode, transistor, and FET in-process screening (see 3.6.1). Each manufacturer shall establish diode,
transistor, and FET screening processes as approved by the qualifying activity. As a minimum, these processes shall
include a 24-hour minimum burn-in at +125°C minimum and may use MIL-STD-750-1 or MIL-STD-883 as a guide.
These processes shall be performed prior to run-in (see 4.8.2.2).
4.7.2 Inspection of product for delivery. Inspection of product for delivery shall consist of group A inspection.
4.7.2.1 Inspection and production lot.
4.7.2.1.1 Inspection lot. An inspection lot shall consist of all the relays of the same specification sheet, and those
of similar design and construction as outlined in 6.3.1.2, manufactured under essentially the same process and
conditions during a manufacturing period of one month maximum. The manufacturer shall define and document the
period for an inspection lot. For purposes of lot formation, all terminal types may be included in the same lot;
however, all lead types which are combined shall have the same method of terminal attachment. All leads in the lot
shall be represented in a similar proportion by samples selected for inspection.
4.7.2.1.2 Production lot. A production lot shall consist of all relays of the same PIN. Manufacture of all parts in the
lot shall have been started, processed, assembled, and tested as a group. Lot identity shall be maintained
throughout the manufacturing cycle.
4.7.2.2 Group A inspection. Group A inspection shall consist of the inspections specified in table V.
4.7.2.2.1 A1, A2, and A4 tests. The A1, A2, and A4 tests shall be performed on a production lot basis on 100
percent of the product supplied under this specification (see footnotes to table V). Relays that do not meet
specification requirements of these groups shall be removed from the lot.
4.7.2.2.1.1 Sampling plan. The tests in A1, A2, and A4 shall be performed on each relay offered for inspection,
except as noted.
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