MIL-PRF-21038F
4.6.2 Group A inspection.
4.6.2.1 C level. For the group A inspection, the manufacturer shall establish and maintain an inspection
system to verify that transformers meet electrical characteristics and visual and mechanical requirements. In-
line or process controls may be part of such a system. The inspection system shall also include criteria for lot
rejection and corrective action. (NOTE: Since the C level is the M level design without the mandatory
conformance inspection system, this product is still expected to meet the environmental qualification type
requirements (e.g., moisture resistance, shock, vibration).)
4.6.2.2 M level. Group A inspections shall consist of the inspections specified in table II, in the order shown.
(NOTE: M level transformers are not subjected to group I.) A sample of transformers shall be selected in
accordance with table III. If one or more defects are found, the lot shall be screened for that defect and defects
removed. Any minor visual or mechanical defects not affecting part performance may be reworked. A new sample
of parts shall be randomly selected again in accordance with table III. If one or more defects are found in the
second sample for the same defect or rejection cause, the lot shall be rejected and shall not be supplied to this
specification.
4.6.2.3 T level. Group A inspections shall consist of the inspections specified in table II, in the order shown.
T level also requires the 100 percent testing shown in group I. If during the 100 percent inspection of group I,
more than 10 percent or 2 units whichever is greater, of the lot is found to be defective, the lot shall be rejected
and not supplied to this level. For group II, T level shall follow the same sampling rules, defects criteria, and
rescreening procedures as M level (see 4.6.2.2).
TABLE II. Group A inspection (M level and T level).
Inspection
Requirement paragraph
Method paragraph
Group I (T level only)
Thermal shock
3.15
4.7.12
Winding continuity
3.11
4.7.8
Electrical characteristics (except impedance)
3.6
4.7.3
Group II (M and T level)
Electrical characteristics 1/
3.6
4.7.3
Visual and mechanical
3.4, 3.21, 3.22
4.7.1
1/ Since T level product has been 100 percent tested for electrical characteristics in group I, group II
sampling for these same tests is not required for T level. Impedance testing for product level T shall be
performed in group II (see 3.1).
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