TASK 70-38-12-250-002

R HIGH FREQUENCY MHz MANUAL EDDY CURRENT INSPECTION OF

TITANIUM ALLOY ROTATING ENGINE HARDWARE
1. General.
A. This document describes the general equipment, techniques,
R and procedures required to conduct high frequency MHz
manual (hand-held) eddy current inspections of rotating
engine hardware manufactured from titanium alloys. The
inspection areas, reject criteria, and specific
requirements are detailed in manual procedures written for
specific hardware.
B. This document describes the general procedure to do the
required inspections. For specific cases where the
procedure described herein cannot be applied as written,
approval for specific exceptions should be obtained in
writing from CFMI to cover the deviating items.
C. The following requirements shall be met by inspection
personnel:
(1) Personnel performing this inspection shall be
certified in accordance with NAS-410 or SNT-TC-1A
or COSAC, or ATA 105, Level 2.
(2) Personnel performing this inspection should receive
practical training in the use of this procedure and
must demonstrate proficiency in the calibration and
evaluation routines before accept/reject authority is
delegated.
(3) Training per this procedure does not imply personnel
certification per NAS-410 or SNT-TC-1A or COSAC,
Procedure EN4179.
D. The following documents shall form a part of this
procedure to the extent specified herein. Unless a
specific issue is specified, the latest revision shall
apply.
(1) Appropriate equipment instruction manuals.
(2) NAS-410 and/or SNT-TC-1A and/or COSAC, EN4179, and/or
ATA 105.
(3) Appropriate Manual procedure.

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 2. Equipment.
A. Instruments.
(1) Eddy Current Instrument.
NOTE: The Eddy Current Instrument must be approved
by CFMI before its use for such inspection; it
must have the following characteristics:
R . Frequency available 2 MHz or 3MHz
. High Pass Filter
available: 10 Hz
.Low pass filter
available 100-200Hz
. Alarm available : visual or audible
. Impedance Plan
available : -
. Input probe plug: shall connect with plug
ref. VEAM 8623 VPT
06A14-15P (8R) (FORSTER)
B. Tooling.
(1) Probes and Fixtures.
Refer to the applicable manual. See figure 1.
(2) Calibration Standard.
Eddy current calibration standard shall be
manufactured from the same material as the part to be
inspected. Obtain this standard from CFMI or use an
approved equivalent. See figure 2. Applicable
manual procedure shall define the standard for each
application.
NOTE: This tooling will be contained in a CFMI
inspection kit. The inspection kit number
shall be identified in the applicable manual
procedure. A complete inspection kit
containing all required tooling can be
obtained from CFMI by contacting the following
address:

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R

Typical Eddy Current Probe and Fixture Setup

(Dovetail Slots Inspection)
Figure 1

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Typical Eddy Current Calibration Standard

(CFMI Supplied or CFMI Approved Equivalent)
Figure 2

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 North & South America, Europe, Middle East, and
and Asia Customers Africa Region Customers
CFMI Inc. Customers CFMI SA Customers
R CFM International CFM International
R Quality Technology Center SNECMA SERVICES
R One Neumann Way, MD: Q8 Manager CFM56 Tooling Programs
R Cincinnati, OH 45215 USA Site de Melun-Montereau
R Attention: Brenda Tenley BP 1936
R Phone: (513) 552-4701 77019 Melun Cedex
R (892 dial com) FRANCE
R Fax: (513) 552-4892
R Email: brenda.tenley@ae.ge.com
3. Materials.
Material Product No.
Teflon Tape Commercially available
0.0035 in. (0,089 mm)
max. thickness
Scotch Brite Pads CP2240 or CP2279
Isopropyl alcohol CP1041
4. Equipment Setup.
A. Connect the selected equipment and allow it to warm up
or as specified by the manufacturer.
5. Probe Preparation.
A. Select the appropriate probe and fixture for the area to
be inspected (reference applicable Service Bulletin or
Shop Manual).
B. Check probe for damage to the coil face and adjacent
area. Also check the centering and traveling fixtures for
damage.
C. Prepare teflon tape for probe wear face as follows:
(1) Lay a strip of tape approximately one inch (2,5 cm)
long on a firm, smooth, clean surface. With a razor
blade cut the tape to a square of approximately
0.250 inch (6,3 mm).

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 NOTE: That size of tape should be sufficient to
completely cover coil face, plus additional
width so that tape edges are slightly off the
probe tip.
(2) Apply the tape tightly across the coil face and
around each side. Refer to figure 3. Smooth all
edges back from the coil.
NOTE: There must be no wrinkles on the tape face or
they will snag on entering the area. If the
tape is wrinkled, it is too large. Remove it,
cut a new smaller piece, and apply the new
piece.
D. Ensure that the probe cable exits straight out the back of
the fixture. Connect the probe to the eddy current
instrument front panel receptacle.
6. Pre-inspection Part Preparation.
A. Visually inspect the area under white light for evidence
of adhering dirt, cracks, rubbing, fretting, etc.
B. Record any abnormal condition.
C. Clean the area(s) by using the materials listed in
paragraph 3. followed by a cloth moistened with an
approved cleaning fluid.
D. Prior to inspection, locate the serial number on the part
and mark this location on the forward side of the part.
This will be the 12 o’clock (start/ref.) position.
7. Equipment Calibration.
NOTE: As a result of differences in notch response resulting
from possible variations in the fabrication process,
calibration standards may have amplitude correction
factors (equivalent responses) applied to them. The
CFMI laboratories will establish these equivalent
responses by comparing the responses from the CFMI
master standard to the response from the subordinate
standard. In cases where an equivalent response is
required, this equivalent response applies to the
calibration only and does not alter the amplitudes
specified for indication rejection limits.

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R

Application of Teflon Tape to Probe Tip

Figure 3

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 A. Connect equipment and set initial controls defined and
documented at time of the validation by CFM International.
B. Place the probe and fixture onto the calibration standard
as specified in manual.
C. Null the eddy current probe on the calibration standard
surface away from the EDM (electro discharge machined)
notch and engraving.
D. Adjust the high pass filter to 10 Hz and the low pass
filter between 100 and 200 Hz according to the equipment
available.
E. Scan the probe across the calibration standard while
indexing the fixture until the EDM notch is detected. The
probe should be scanned at a speed equivalent to that used
for the inspection. Both should achieve a probe speed as
defined in the appropriate Service Bulletin or Shop Manual.
F. Translate the probe back and forth across the entire EDM
notch to determine where the maximum amplitudes are
achieved.
G. Adjust the rotation control until the notch indication is
positioned vertical. Refer to figure 4.
H. Adjust gain controls to achieve the calibration amplitude
of 80 % (full screen) or the value engraved onto the
calibration standard.
Re-null after any gain or rotation adjustment.
NOTE: For re-nulling, the coil must be well off the EDM
notch and away from any edge of the standard.
NOTE: The full screen amplitude value obtained must not
be less than the engraved values of the calibration
standard without exceeding them of plus 5 percent.
8. Part Inspection.
A. Complete pre-inspection part preparation in accordance
with pararagraph 6.

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Typical CRT Displays For General Notch Indication

Rotation Adjustment
Figure 4

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 B. Calibrate all equipment in accordance with paragraph 7.
C. Inspect all areas per the appropriate scan plans as
identified by specific manual procedures and as follows.
(1) Assure the teflon tape is still covering the coil on
the end of the probe. Replace if it is worn or
wrinkled and recheck calibration.
(2) Reassemble and/or adjust the probe and fixture to the
configuration required to inspect the area(s).
(3) Place the probe completely within the area so the
coil is away from any edges and re-null instrument.
(4) Scan the entire area to be inspected.
D. If any indications exceeding the requirements of
paragraph 10. are found, mark the area for evaluation and
do this evaluation per paragraph 11.
NOTE: Check the teflon tape if a sudden noise increase is
noted. Replace it if worn or wrinkled and recheck
calibration.
9. Calibration Check.
A. After completion of the part inspection, or after
intervals not to exceed 2 hours, check the calibration of
the system.
(1) If the calibration repeats within plus or minus
5 percent of full screen amplitude representative of
80 % or of the engraved value of the calibration
standard, the test is acceptable.
(2) If the amplitude of the response has increased by more
than 5 percent recalibrate as required, the test is
acceptable.
(3) If the amplitude of the response has decreased by more
than 5 % compared to 80 % or the engraved value,
repeat the calibration procedure and re-inspect all
parts inspected since the previous calibration.

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 10. Inspection Requirements.
Refer to the applicable manual as specified for the inspection
being performed. The inspection requirements shall be as
specified in that document.
11. Indication Evaluation.
NOTE: The optimum time to perform these evaluations is at the
time the indication is found.
A. Check probe for missing Teflon tape or damage.
B. Check Probe Calibration per paragraph 7.
(1) If the calibration repeats within zero/plus 5 percent
of full screen amplitude representative of the
engraved value on the calibration standard, the probe
calibration is considered as acceptable.
(2) If the amplitude of the response representative of
the engraved value on the calibration standard has
decreased, repeat the calibration procedure and
re-inspect all incriminated areas inspected since
previous calibration.
(3) If the amplitude of the response representative of
the engraved value on the calibration standard has
increased by more than 5 percent, repeat the
calibration procedure and re-inspect the incriminated
areas previously found rejectable.
C. Carefully examine the area under evaluation in bright
white light using a glass of 5 to 10 power. Note any
unusual conditions such as discoloration, scratches, score
marks, sharp edges, uneven surfaces, etc. Record these
conditions on the inspection summary sheet. Refer to
figure 5.
D. For an area with indication(s) exceeding requirements of
paragraph 10., clean again the incriminated area with
Scotch Brite pad (CP2240 or CP2279) and a cloth moistened
with Isopropyl alcohol (CP1041) and re-inspect the area.
If the indication remains, it is considered repeatable and
should be evaluated as stated below. If not, proceed to
the next indication.
E. For all repeatable indications, record the amplitude and
the incriminated location on the appropriate inspection
data sheet. Refer to figure 5.

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Eddy Current Inspection Data Sheet

Figure 5

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 F. Carefully re-clean the area of the indication per paragraph
11.D. of this document. Ensure no protruding material
exists in the area.
G. Re-inspect the area. If the indication response amplitude
remains the same after cleaning, repeat paragraph 11.D.
one time. If it still has not reduced in amplitude,
proceed to paragraph 11.H. If the reponse amplitude is
reduced but still meets paragraph 10. requirements, the
area may be re-cleaned and re-evaluated since the response
is most likely due to surface contamination. If the
indication is no longer there, or if its amplitude is
below paragraph 10. requirements, note that fact on the
data sheet and proceed with the evaluation of the next
indication. If the indication(s) remain(s) but is part of
a general background noise, note that fact in the
"Comments" section of the Data Sheet. See figure 5.
H. If the indication response amplitude has not reduced or
will not reduce to below paragraph 10. requirements, the
part shall be rejected for engineering evaluation and
disposition.
12. Records.
A. As a minimum, the following information shall be
permanently written. Figure 5 shows a basic and
recommended type of inspection summary sheet.
B. All inspection records should be kept with permanent
records of the part.

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