TM 1-1520-253-23
NOTE
If during setup the flying spot deflects upward or to the side when the probe passes over the bad
part, instead of the desired down deflection toward the alarm box, press SPCL and toggle to a
different phase setting (90,180, or 270), and repeat d. and e. Continue to try phase setting until
the flying spot moves in the desired down direction.
f.
Place probe on good area of test block and press RUN. Flying spot should be near the top-center of the
ACTIVE screen. If not, press NULL. Slide probe from good to void area and note response from flying spot.
This response should provide both amplitude (vertical) and phase (horizontal) movement. The default
gate/alarm setting may be incorrect for this setup. Turn off or reset gate/alarm as desired.
g. The Bondmaster is programmed to automatically set test parameters to a start-up or initial bond test. By
following the steps outlined above, adjustments to the FREQ, GAIN, and ALARM can help to refine the
selectivity in locating defects among differing bonded metallic and composite materials.
2.11.3.6 Inspection Procedure. Refer to Bond Test Method, paragraph 1.4.6 and inspection areas shown in Figure 2-11.
a. Skin-to-Honeycomb Voids. Place probe on main rotor blade in location where test for skin-to-honeycomb bond
separation is desired and press NULL. Move probe from good to suspect area and note response. A strong
amplitude change with phase shift similar to the test block is indicative of a void. This setup is very sensitive
to thin skin-to-core bonding. Move the probe slowly over the skin and note the slight amplitude change
(bounce) as the probe senses alternately the honeycomb cell nodes and cell walls.
NOTE
The basic setup provided also selects a frequency unit provided a satisfactory inspection for
voids associated with skin-to-spar, skin-to-trailing edge, doubler-to-doubler and doubler-to-
skin, and trim tab bonding. For the inspection of bonding voids to the spar, setup on Test Block
Composite Defect Standard #3 may provide some advantage.
b. Use the NULL and GAIN adjustments to reset the ACTIVE screen for the areas to be inspected (do not go back
to SET mode). Also, compare similar areas. For example, to check for spar-to-skin voids, check front and
back of blade in the same area, or check another blade in the same area. Observe that, when moving the
probe chordwise from the spar to the trailing edge, the transitions at the spar-to-honeycomb and the
honeycomb-to-trailing edge strip are easily detected. When inspecting these areas, adjust the NULL and GAIN
and move the probe carefully along the transition using a straight edge or other guide. A localized phase and
amplitude shift similar to the test block indicates a void.
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