PART 4 - ULTRASONIC
ENGINE COWL BONDED HONEYCOMB ACOUSTIC PANELS
1. Purpose
A. To detect delamination (disbonded area) of the exposed perforated aluminum face sheet from the
honeycomb in the bonded honeycomb engine cowl acoustic panels, 65B91524.
2. Equipment
A. Sondicator Model S-2 or Model S-2B.
B. Reference Standard - Use a section of panel of similar construction to that being inspected and
representative of both bonded and disbonded areas. A disbonded area one inch in diameter or larger is
required for a disbond reference standard.
3. Prepare for the Inspection
A. This inspection can be performed on the airplane with the part in place. No removals are required.
B. Clean any grit or dust from inspection surface.
4. Instrument Calibration
A. Sondicator Model S-2B
(1) This model operates like the Model S-2 except that it is battery powered and requires no warmup
time. Set selector switch to phase/+amplitude and calibrate per instructions for the model S-2.
Use of audio is optional.
B. Sondicator Model S-2
(1) Turn on instrument and allow 3 to 5 minutes warmup time.
(2) Place probe on a bonded portion of the reference standard. Maintain constant pressure on the
transducer.
(3) Set both amplitude and phase controls to zero, adjust amplitude control until meter reads
midscale then adjust phase control until meter reads midscale. Readjust amplitude to midscale, if
necessary. Instrument is now calibrated for inspection.
(4) Place probe on a disbonded area and note meter deflection.
(5) For perforated aluminum face sheet, disbonds will be indicated by an increase in amplitude meter
reading to approximately full scale. Meter increases of less than 30% from midscale are not
considered significant. Phase change will usually be negligible.
5. Inspection Procedure
A. Grid area to be inspected into approximately 4-inch squares.
B. Place transducer on the part at the predetermined 4-inch intervals. (Do not slide transducer).
C. Maintain same pressure on transducer as established during calibration.
D. Compare readings obtained at each spot to that obtained during calibration in Paragraph 4.
6. Inspection Results
A. Meter readings greater than 80% are considered disbond.
B. Mark limits of any disbonded area detected.
747
NONDESTRUCTIVE TEST MANUAL
PART 4 54-30-01
Page 1
Nov 15/2015D6-7170
ECCN 9E991 BOEING PROPRIETARY - Copyright © Unpublished Work - See title page for details
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