MIL-DTL-14824C(AR)
cuts prior to measurements for depth of sidewall contact to
determine compliance with the requirements of 3.6.2
4.4.4 Ultrasonic inspection. The projectile body shall be
ultrasonically inspected prior to band seat machining and nose
threading using equipment detailed in 4.4.4.1. Ultrasonic energy
shall be used at right angles to assure that orientation does not
prevent detection of a defect. Standards, in accordance with
4.4.4.3, shall be used to check the effectiveness of the
inspection process. Any projectile failing to meet the
requirements of 3.7 shall be classed defective and removed from
the lot. All projectiles rejected by ultrasonic inspection shall
be visually inspected at the location of the ultrasonic
indication. An ultrasonic critical defect shall be defined as
any ultrasonic reject that has a visual crack or pipe or a visual
defect other than a crack or pipe (lap, fold, seam, etc.) that
has an ultrasonic signal that is twice the level of the
ultrasonic standard notch for that area. Visual defects other
than cracks or piping shall be statically evaluated by a level II
(or higher) qualified inspector to determine if a critical defect
exists. Visual defects other than cracks or piping with less
than twice the level of the ultrasonic standard notch for that
area are not considered critical, but shall be rejected as major
defects. Critical defect determination will be accomplished
within 24 hours of the observation. Stamp the letter "U" on each
projectile accepted by ultrasonic inspection.
4.4.4.1 Ultrasonic test equipment and procedures. The
ultrasonic inspection shall be performed in accordance with dwg.
9280419 with the use of a liquid to assure a reliable coupling to
transmit ultrasonic energy. Should a stream or thin film of
liquid be used to couple this energy, controls shall be used to
monitor the coupling and assure its effectiveness. Such
monitoring is not required if submergence in a liquid is used.
Using ultrasonic energy at right angles requires at least two
separate sources of ultrasonic energy. This means that in the
wall and bourrelet ultrasonic regions, ultrasonic energy shall
move within the walls of the projectile with separate significant
axial or circumferential components of velocity to detect flaws
located on the outside, inside or within the walls. For the base
region, significant ultrasonic velocity components shall
separately be radial and circumferential. Criteria for detection
of cracks are machined notches which simulate actual larger
cracks. Details are contained on drawing 9280420. All notches
machined on the standard are targets for rejection. That is, any
projectile that sends back an echo signal that is greater than or
equal to the signal from the standard shall be rejected. Relief
portions of radially oriented notches where the full depth
approaches the surface are not inspection criteria.
4.4.4.2 Calibration and operation procedures and equipment.
Prior to initiation of ultrasonic inspection, the contractor
shall submit, as part of the AIE submittal, for written approval
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