# Brantly Service Bulletin 111: No revision named - Rights: © Brantly. Filed by the FAA in regulations.gov docket FAA-2012-1093; AD 2014-20-16 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication. - Document: [Brantly Service Bulletin 111](https://openairdocs.org/service-documents/brantly/sb-111.md) - Title as filed: U.S. DOT/FAA - Brantly Service Bulletin No 111 and B-2 MRB Root Skin Inspection ET002 - Pages: 11 - PDF: https://openairdocs.org/files/sha256/ff/9f/ff9fd875ef929ddb79eab1cc929b39d3661d6efaa65d48a6e23e62844da1bd42 - Page: https://openairdocs.org/service-documents/brantly/sb-111/file/ff9fd875ef92 ## Text This text is OCR from a scan. OCR can misread letters and numbers. Each page's text from the PDF; open the PDF at a page with #page=N. ### Page 1 (OCR) BRANTLY INTERNATIONAL INC. SERVICE BULLETIN No: 111 SERVICE BULLETIN REVISION: ~ PAGE: 1/4 SERVICE BULLETIN No: 111 February 10, 2011 REVISION: ~ SUBJECT: Outboard Main Rotor Blades MODELS AFFECTED: See below. TIME OF COMPLIANCE: See below. FAA APPROVAL: To be submitted to the FAA for approval Introduction The Brantly Maintenance Manuals for the B2 series helicopters call out an inspection for the outboard main rotor blades in section 1.8.1 Preflight and Daily Inspections. Listed in these sections are criteria for inspecting the blades for cracks and damage. Cracks in all B2 series main rotor blades are considered unairworthy and are cause for blade replacement. Service Letter 110 was issued as a reminder of these inspections. This service bulletin supersedes and cancels the sections of the maintenance manuals mentioned above as well as Service Letter 110. In addition, this service bulletin supersedes all other service information published for outboard main rotor blade inspections before the approval date of this service bulletin for p/n 248-101, 248-202, and 248-404. The table shown below shows each superseded and canceled sections and documents. Document Name Revision Section Status Brantly B2 and B2A Maint. Manual March 1963 1.8.1 a,b,c,d,e,f,g,h, & Fig 2, Superseded/ Canceled Pg 6A Rev. S, Mar. 1965 Brantly B2B Maint. Manual May 15, 1991 1.8.1 a,b,c,d,e,l, & Fig II, Pg Superseded/ Canceled 4, Rev ~ Brantly Service Letter 110 ~ Oct 31, 2005 All Superseded/ Canceled It is suspected that some outboard main rotor blades have been rebuilt in the field. Rebuilding may only be accomplished by the manufacturer and is not recommended or approved to perform in the field. Any owner/operator that suspects that a blade has been rebuilt or repaired without FAA approval should remove the blade from service and report it to the FAA through the Suspected Unapproved Parts Program (SUP) or through the aviation authority in the applicable country. Repairs made to outboard main rotor blades must meet or exceed the original design strength of the blade and require FAA approval. Applicability Applies to models B-2, B-2A, or B-2B that have main rotor blades p/n 248-101, 248-202, and 248-404 installed. Compliance For Outboard Main Rotor Blades P/N 248-101 and 248-202, before further flight, comply with sections 1 and 2 of this service bulletin. Thereafter at intervals not to exceed 300 flight hours or 5 calendar years, whichever occurs first comply with section 1 and at intervals not to exceed 25 flight hours comply with section 2. Also comply section 3 of this service bulletin before the first flight of each day. For Outboard Main Rotor Blades P/N 248-404 with less than 10 years time in service or 1000 flight hours, comply with section 3 of this service bulletin before the first flight of each day. ### Page 2 (OCR) BRANTLY INTERNATIONAL INC. SERVICE BULLETIN No: 111 SERVICE BULLETIN REVISION: ~ PAGE: 2/4 For Outboard Main Rotor Blades P/N 248-404 with more than 10 years time in service or 1000 flight hours, before further flight, comply with section 1 and 2 of this service bulletin. Thereafter at intervals not to exceed 300 flight hours or 5 calendar years, whichever occurs first comply with section 1 and at intervals not to exceed 25 flight hours comply with section 2. Also comply with section 3 of this service bulletin before the flight of each day. Contact: Service Department (service@brantly.com) Phone 972.829.4600 Brantly International Inc. 621 S. Royal Lane; Suite 100 Coppell, TX 75019-3805 USA 1 Crack Inspection (300 Hour Inspection) 1.1 Remove the outboard main rotor blade. Clean surface to be inspected. Remove any contaminates that might interfere with the discovery of existing surface indications. Inspect the outboard main rotor blades for cracks using the Eddy Current Procedure ET002 attached with this service bulletin. 1.2 No cracks or nicks are permitted. No creases, wrinkles or bends are permitted in the trailing edge of the blades. Verify adequate edge distance between holes such that no additional holes have been added or extra rivets used to fill stop drilled holes in the root fitting. Any blade that has cracks (especially around the root of the blade), extra rivets, or stop drilled holes must be removed from service. If any of these defects are found, remove the blade from service and replace with an airworthy part. Record the results in 2 Delamination Inspections (25 Hour Inspection) 2.1 Remove the outboard main rotor blade. Clean surface to be inspected. Remove any contaminates that might interfere with the discovery of existing surface indications. Use a suitable light and a 10X magnifying glass to inspect for cracks in the main rotor blade. Pay particular attention to areas around rivet holes, the blade root area, and the trailing edge. 2.2 No cracks or nicks are permitted. No creases, wrinkles or bends are permitted in the trailing edge of the blades. Verify adequate edge distance between holes such that no additional holes have been added or extra rivets used to fill stop drilled holes in the root fitting. Any blade that has cracks (especially around the root of the blade), extra rivets, or stop drilled holes must be removed from service. If any of these defects are found, remove the blade from service and replace with an airworthy part. Record the results in section 4 of this service bulletin. 2.3 With the outboard main rotor blade removed, inspect the blade for delamination using a tap test. 2.4 Use a metallic coin or tap hammer to lightly tap the blade in the areas that are bonded. Pay particular attention to the inboard 12 inches (.304m) on the top and bottom. Mark all delaminated areas with a grease pencil or chalk. NOTE Delaminated areas will have a duller, low pitched sound when compared to areas that are not de- laminated. They may also have a spongy or loose feeling when pressed with the hand. 2.5 No delamination is permitted on the inboard 12 inches (.305m). Delamination is permitted outboard of this area provided the total delaminated areas do not exceed 10 in? (.254m?). Record the results in section 4. ### Page 3 (OCR) BRANTLY INTERNATIONAL INC. SERVICE BULLETIN No: 111 SERVICE BULLETIN REVISION: ~ PAGE: 3/4 3 Daily Inspections 3.1 Before the first flight of each day, visually inspect the outboard main rotor blade for cracks and wrinkling of the skin. Pay particular attention to the blade root area, the area around the lead/ag damper mounting fork, and the blade trailing edge. 3.2 No cracks, nicks, or wrinkling of the skin are permitted. No creases or bends are permitted in the trailing edge of the blades. If any of these defects are found, remove the blade from service and replace with an airworthy part. ### Page 4 (OCR) BRANTLY INTERNATIONAL INC. SERVICE BULLETIN No: 111 SERVICE BULLETIN REVISION: ~ PAGE: 4/4 4 Inspection Report for SB-111 Please complete this report for each outboard main rotor blade and send it to Brantly Int. Use the contact information given in this service bulletin. Describe the cracks and delamination as much as possible and use the figure to create a sketch of their locations. Helicopter Information Reg. # Serial # TTIS Date Name Address Tel. E-mail Blade Information P/N Serial # Blade TTIS Blade TT @ Installation Helicopter TT @ Blade Installation 12 n (.3)48r; No Delamination Bonded Area Permitted In This Area Results/ Description of Cracks and Delamination ### Page 5 (OCR) Brantly International B-2 Main Rotor Blade Root Skin Inspection page 1 of 7 1. Technique Number: ET002 3. Component to be examined: P/N 248-101, 248-202, and 248-404 main rotor blade (MRB) assemblies. 2. Technique Date: 11/07 4. Area of Examination: At fastener locations in the upper and lower surfaces of the 2024-T3 aluminum skin. 5. Purpose of Examination: To detect skin cracks propagating from the fastener holes at various locations, thus preventing separation of the skin assembly and possible control loss of the aircraft. 6. Technique Written By: Todd L. Jackson 7. Required equipment and tooling: a. A single channel impedance plane eddy current instrument. 1. The instrument used to develop this procedure was the GE Phasec 2D with a 12 pin LEMO-to-BNC connector adaptor. A comparable impedance plane instrument that that can obtain equivalent sensitivity can be used. b. An absolute, shielded, microtip pencil probe with a straight, 45 or 90 degree drop and a BNC-to microdot cable. 1. The probe used to develop this procedure was a MMP 445-40FX 50-500 KHZ and can be obtained from Olympus NDT (see paragraph d. 1. for contact information). Comparable probe with a microtip diameter may be used. 2. Cover probe coil wear surface with Teflon Tape, Temp-R-Tape, Type T, .006 inch thick by 1 inch wide adhesive backed or equivalent-available from: Furon Furon-CHR Division 29982 Ivy Glenn Drive or 407 East Street Laguna Niguel, CA 92677-2004 New Haven, CT 06509-9988 c. A circle template made of non-conducting material to guide the probe concentrically around the fasteners will be used. A Pickett No. 2100i circles inking template, commonly found at drafting supply stores, was used to develop this procedure. d. A calibration standard PN. ET002 (see figure 1). 1. Can be locally manufactured or obtained from Olympus NDT (formerly NDT Engineering Corporation) at: 19620 Russell Rd Kent, WA 98032 Phone (1) (253) 872-0857 e. Suitable work surface to position the removed blade for inspection. 8. Basic Eddy Current Instrument Operating Parameters (Phasec 2D): a. Turn Instrument on by depressing the on (green) button. b. Press the menu button to access the operating parameters. Verify that the following parameters are set for initial instrument calibration. Refer to the instrument operating manual for parameter adjustment procedure. Note- The parameters listed below will vary slightly in description from one instrument make and model to another. (FREQ) (ALARM) (MEMORY) (1) GAIN XY1 set to 30.0/45.0 Optional See Note 1 (2) PHASE 1° set to 0 (2) FREQ1 kHz set to 200 kHz (PROBE) (3) Filter set to BP LOCK. MODE set to Normal Single. (4) HP/LP filters set to DC/30.0. (TRACE DISP) PROBE ID N/A, Unknown. (5) INPUT GAIN1 set to High. (1) DISPLAY set to Spot. LOAD uH set to 120 or balance hold. (6) PROBE1 set to Absolute. (2) GRATICULLE set to Grid 2. DRIVE dB set to +8 (OUTPUT) (3) SPOT XY set to 115/-30 (4) SPOT INFO set to None. BAL/CLR MOD set to Single. (1) ANALOG O/P 1 set to X1. (5) PERSIST set to 5.0 s. (2) ANALOG O/P 2 set to X1. (6) SWEEP set to 5.0 s. ### Page 6 (OCR) Brantly International B-2 Main Rotor Blade Root Skin Inspection page 2 of 7 9. Overview of the Inspection: a. Surface eddy current inspect to detect cracks in the skin assembly on the upper and lower surfaces of the main rotor blade (MRB), adjacent to the heads of the MS20426-AD3 and AD4 rivets in the following areas (see Figure 2): 1. At the riveted area common to the hinge block attach fitting, sub-divided into fastener spacing configurations, and 2. at the riveted row common to the spar. Figure 1- Calibration Standard ET002 Details - 3.00" .125" 1.30" 4 4.50"→ 50"→*.50"→+.50"*.50"* FLAG NOTES MACHINED OUT OF .125 2024- 'NOTCH D 1 T3 ALUMINUM PLATE. 1.00" 100° COUNTER SINK ALL FASTENER LOCATIONS .130" EXCEPT LOCATIONS 5. .020" FABRICATE FROM .016" THICK MAX 2 2024-T3 CLAD ALUMINUM SHEET. 100° DIMPLE COUNTER SINK ALL EXCEPT .980" MIN. NOTCH C 3.00" FASTENER LOCATIONS 5. MS20426-AD3 RIVETS (3/32" 3 DIAMETER). MAKE SHOP HEADS ½ D X 2 D STANDARD NOTCH B NOTCH A 2.00" MS20426-AD4 RIVETS (1/8" 50" 4 DIAMETER). MAKE SHOP HEADS ½ D X 2 D STANDARD 5 STACK DRILL .200" DIAMETER 50" AND DEBUR. ET002 -XXX VIBRO-ETCH OR ELECTRO- 6 ETCH PART NUMBER AND *.60"→ 80" *.50"- •.50"→ .016" SERIAL NUMBER INTO TOP -.300" .30" .109" SURFACE NOTCH DIMENSIONS (INCHES) NOTCH LENGTH WIDTH DEPTH A 200" MEASURED (.035" FROM EDGE OF COUNTER SINK DIMPLE) .010" MAXIMUM THROUGH EDGE OF FASTENER HOLE TO EDGE OF FASTENER HOLE .010" MAXIMUM THROUGH EDGE OF FASTENER HOLE TO EDGE OF SHEET METAL .010" MAXIMUM THROUGH D EDGE OF FASTENER HOLE TO EDGE OF SHEET METAL 010" MAXIMUM THROUGH NOTE-NOTCH LOCATIONS MUST BE WITHIN +/- 0.005 OF THE CENTERLINE OF THE HOLE. DIMENSIONAL TOLERANCE (INCHES) XXXX = +/- 0.005 XXX = +/- 0.025 X.X = +/- 0.050 ANGLES: +/- 1.0 DEGREE SURFACE ROUGHNESS = 63 Ra OR BETTER ### Page 7 (OCR) Brantly International B-2 Main Rotor Blade Root Skin Inspection page 3 of 7 Figure 2: Fastener Locations at Hinge Block Fitting and Spar Areas SKIN-TO-SPAR FASTENERS IN AREA "B" (SEE FIGURE 3) LEADING SKIN FORWARD EDGE EDGE SKIN SKIN SKIN-TO-HINGE BLOCK FASTENER AREA "A" TRAILING (SEE FIGURE 3) BLADE ROOT < BLADE TIP EDGE Figure 3: Fastener Identification and Corresponding Probe Calibration Positions on ET002 SCAN PATTERN SKIN EDGE LINE PROBE PROBE USING PROBE GUIDE AREA "B" FASTENERS POSITION 8 POSITION 9 (SEE FIGURE 5) @ NOTCH D • PROBE POSITION •0 POSITION 2 PROBE 9 (O O PROBE POSITION 1 O DAMPENER ATTACH HOLE SPAR-TO-HINGE PROBE AREA "A", SEE PAR. 10 AND 11 L BLOCK LINE_ POSITION 3 @ NOTCH C • INSUFFICIENTILY SPACED AREA "A" FASTENERS FASTENERS, AREA "A", SEE PAR. 12 AND 13 -1002 @SUFFICIENTLY SPACED KNOWN LOCATIONS OF PROBE PROBE FASTENERS, AREA "A", SEE PAR. 14 AND 15 SKIN CRACKS EMANATING FROM FASTENERS POSITION 4 PROBE PROBE POSITION 7 O SKIN-TO-SPAR FASTENERS LOCATED IN AREA "A" POSITION 5 POSITION 6 AREA "B", SEE PAR. 16 AND 17 @ NOTCH B @ NOTCH A 10. Instrument Calibration for Inspection of Skin around Dampener Attach Hole (Area "A") a. Turn instrument on and ensure the basic operating parameters are set (see paragraph 8). b. Place Teflon tape over probe coil. Connect the probe to the instrument and select a balance load. c. Place the probe on position 1 of the ET002 reference standard, and press balance/lift-off. If needed, adjust Spot XY position to bring flying dot into position as shown in figure 4. d. Lift the probe coil approximately 1" from the surface of the reference standard. The signal trace should move horizontally from right to left on the screen from the balance point shown in figure 4. Note: The lift-off phase angle will be automatically set as shown in figure 4, when balance/lift off is pressed and held. If the instrument does not have an "auto phase" feature, rotate the phase angle until the desired results are obtained. e. Place the probe on probe position 2 of the ET002 reference standard (see figure 3) and scan around the hole using the circle template as a probe guide as shown in figure 5. Observe the screen while scanning. The flying dot should not move more than 1-2 division lines vertically or horizontally from the balance point. Note: If the dot drifts more than 1-2 divisions horizontally, the probe may be tilted excessively. If the dot drifts more than 1-2 divisions vertically, it is positioned too close to the edge of the fastener. f. Use the same circle template hole to scan around the hole at probe position 3 and over notch C (see figure 3). The signal trace should look similar to that shown in figure 4. Adjust the instrument gain to obtain an 80% screen height vertical movement from the notch. ### Page 8 (OCR) Brantly International B-2 Main Rotor Blade Root Skin Inspection page 4 of 7 Figure 4: Screen Presentations from Lift-Off and Notches A, B and C VERTICAL (Y) DIVISION LINES TYPICAL NOTCH SIGNAL FROM NOTCHS A, B AND C OR CRACK SIGNAL (PROBE POSITIONS 3, 5 AND 6) 180% REJECT OR ALARM LEVEL - 50% LIFT-OFF LINE THE FLYING DOT SHOULD NOT MOVE MORE FLYING DOT THAN 1-2 DIVISIONS VERTICALLY OR 20% HORIZONTALY FROM BALANCE POINT DURING SCAN OVER DEFECT FREE AREA HORIZONTAL (X) DIVISION LINES Figure 5: Proper Circle Selection for Probe Guide CIRCULAR SCAN PATTERN CIRCLE TEMPLATE USED AS A PROBE GUIDE MICRO TIP PROBE MICRO TIP PROBE ET002 FASTENER CALIBRATION HEAD STANDARD CALIBRATION NOTCH "A CALIBRATION NOTCH "C" 11. Inspection of Skin around Dampener Attach Hole (Area "A") a. Place the same circle template hole (selected in step e. of paragraph 10.) concentrically over dampener hole as shown in figure 5. b. Press balance/lift off to balance the instrument, if needed. Adjust Spot XY position, if needed, to bring flying dot into position as shown in figure 4. c. Scan probe around the hole while observing the instrument screen. d. Turn MRB over and repeat the preceding steps on the opposite side of the blade. e. Any signal obtained in preceding steps of this paragraph that exhibits a rapid upscale vertical movement equal to or exceeding 50% screen height will be cause for rejection. f. Determine the length or end(s) of the crack by scanning back and forth across the length until the vertical trace returns to the balance point and mark location. Measure and record the location and length of the crack. ### Page 9 (OCR) Brantly International B-2 Main Rotor Blade Root Skin Inspection page 5 of 7 12. Instrument Calibration for Inspection of Skin adjacent to the Insufficiently Spaced Fasteners (Area "A") a. Turn instrument on and ensure the basic operating parameters are set (see paragraph 8). b. Place Teflon tape over probe coil. Connect the probe to the instrument and select a balance load. c. Place the probe on position 1 of the ET002 reference standard, and press balance/lift-off. If needed, adjust Spot XY position to bring flying dot into position as shown in figure 4. d. Lift the probe coil approximately 1" from the surface of the reference standard. The signal trace should move horizontally from right to left on the screen from the balance point shown in figure 4. Note: The lift-off phase angle will be automatically set as shown in figure 4, when balance/lift off is pressed and held. If the instrument does not have an "auto phase" feature, rotate the phase angle until the desired results are obtained. Place the probe on position 4 of the ET002 reference standard (see figure 3) and scan around the hole using the circle template as a probe guide as shown in figure 5. Observe the screen while scanning. The flying dot should not move more than 1-2 division lines vertically or horizontally from the balance point. Note: If the dot drifts more than 1-2 divisions horizontally, the probe may be tilted excessively. If the dot drifts more than 1-2 divisions vertically, it is positioned too close to the edge of the fastener. f. Use the same circle template hole to scan around the fastener at probe position 5 and over notch B. The signal trace should look similar to that shown in figure 4. Adjust the instrument gain to obtain an 80% screen height vertical movement from the notch. 13. Inspection of Skin adjacent to the Insufficiently Spaced Fasteners (Area "A") a. Place the same circle template hole (selected in step e. of paragraph 12.) concentrically over the fastener adjacent to the skin being inspected (similar to the example given in figure 5). b. Press balance/lift off to balance the instrument. If needed, adjust Spot XY position to bring flying dot into position as shown in figure 4. c. Scan probe around the fastener while observing the instrument screen. d. Repeat the preceding steps of this paragraph until the skin is inspected at all like spaced fasteners located in Area e. Turn MRB over repeat preceding steps of this paragraph until the skin is inspected at all like spaced fastener locations in Area "A". e. Any signal obtained in preceding steps of this paragraph that exhibits a rapid upscale vertical movement equal to or exceeding 50% screen height will be cause for rejection. f. Determine the length or end(s) of the crack by scanning back and forth across the length until the vertical trace returns to the balance point and mark location. Measure and record the location and length of the crack. 14. Instrument Calibration for Inspection of Skin adjacent to the Sufficiently Spaced Fasteners (Area "A") a. Turn instrument on and ensure the basic operating parameters are set (see paragraph 8). Place Teflon tape over probe coil. Connect the probe to the instrument and select a balance load. b. Place the probe on position 1 of the ET002 reference standard, and press balance/lift-off. If needed, adjust Spot XY position to bring flying dot into position as shown in figure 4. c. Lift the probe coil approximately 1" from the surface of the reference standard. The signal trace should move horizontally from right to left on the screen from the balance point shown in figure 4. Note: The lift-off phase angle should be automatically set as shown in figure 4, when balance/lift off is pressed and held. If the instrument does not have an "auto phase" feature, rotate the phase angle until the desired results are obtained. Continued on page 6 ### Page 10 (OCR) Brantly International B-2 Main Rotor Blade Root Skin Inspection page 6 of 7 14. Instrument Calibration for Inspection of Skin Adjacent to the Sufficiently Spaced Fasteners (Area "A") Continued from page 5. d. Place the probe on position 6 of the ET002 reference standard (see figure 3) and scan around the fastener using the circle template as a probe guide as shown in figure 5. Observe the screen while scanning. The flying dot should not move more than 1-2 division lines vertically or horizontally from the balance point. Note: If the dot drifts more than 1-2 divisions horizontally, the probe may be tilted excessively. If the dot drifts more than 1-2 divisions vertically, it is positioned too close to the edge of the fastener. e. Use the same circle template hole to scan around the fastener at probe position 7 and over notch A (see figure 3). The signal trace should look similar to that shown in figure 4. Adjust the instrument gain to obtain an 80% screen height vertical movement from the notch. 15. Inspection of Skin Adjacent to the Sufficiently Spaced Fasteners (Area "A") a. Place the same circle template hole (selected in step d. of paragraph 14.) concentrically over the fastener adjacent to the skin being inspected (similar to the example given in figure 5). b. Press balance/lift off to balance the instrument. If needed, adjust Spot XY position to bring flying dot into position as shown in figure 4. c. Scan probe around the fastener while observing the instrument screen. d. Repeat the preceding steps of this paragraph until the skin is inspected at all like spaced fasteners located in Area "A". e. Turn MRB over repeat the preceding steps of this paragraph until the skin is inspected at all like spaced fastener locations in Area "A" f. Any signal obtained in preceding steps of this paragraph that exhibits a rapid upscale vertical movement equal to or exceeding 50% screen height will be cause for rejection. g. Determine the length or end(s) of the crack by scanning back and forth across the length until the vertical trace returns to the balance point and mark location. Measure and record the location and length of the crack. 16. Instrument Calibration for Inspection of Skin Adjacent to the Skin-to-spar Fasteners (Area "B") a. Turn instrument on and ensure the basic operating parameters are set (see paragraph 8). b. Place Teflon tape over probe coil. Connect the probe to the instrument and select a balance load. C. Place the probe on position 1 of the ET002 reference standard, and press balance/lift-off. If needed, adjust Spot XY position to bring flying dot into position as shown in figure 4. d. Lift the probe coil approximately 1" from the surface of the reference standard. The signal trace should move horizontally from right to left on the screen from the balance point shown in figure 4. Note: The lift-off phase angle will be automatically set as shown in figure 4, when balance/lift off is pressed and held. If the instrument does not have an "auto phase" feature, rotate the phase angle until the desired results are obtained. e. Place the probe on position 8 of the ET002 reference standard (see figure 7) and scan around the fastener using the circle template as a probe guide as shown in figure 5. Observe the screen while scanning. The flying dot should not move more than 1-2 division lines vertically or horizontally from the balance point. Note: If the dot drifts more than 1-2 divisions horizontally, the probe may be tilted excessively. If the dot drifts more than 1-2 divisions vertically, it is positioned too close to the edge of the fastener or the edge of the skin. A signal (like the one shown in figure 6) is caused by the probe being in close proximity to the edge of the skin and must not be confused with the notch signal or a crack. f. Use the same circle template hole to scan around the hole at probe position 9 and over notch D (see figure 6). The signal trace should look similar to that shown in figure 6. Adjust the instrument gain to obtain an 80% screen height vertical movement from the notch. ### Page 11 (OCR) Brantly International B-2 Main Rotor Blade Root Skin Inspection page 7 of 7 Figure 6: Screen Presentations from Lift-Off, Skin Edge and Notch D VERTICAL (Y) DIVISION LINES TYPICAL NOTCH D..... SIGNAL FROM NOTCHS A, B AND C OR CRACK SIGNAL (PROBE POSITIONS 3, 5 AND 6) 80% REJECT OR ALARM LEVEL 50% EDGE OFSKIN SIGNAL THE FLYING DOT SHOULD NOT MOVE MORE LIFT-OFF LINE , FLYING DOT THAN 1-2 DIVISIONS VERTICALLY OR 20% HORIZONTALY FROM BALANCE POINT DURING SCAN OVER DEFECT FREE AREA HORIZONTAL (X) DIVISION LINES Figure 7: Scan Technique around Area "B" Fasteners CIRCULAR SCAN PATTERN MICRO TIP PROBE ET002 CIRCLE TEMPLATE USED CALIBRATION FASTENER AS A PROBE GUIDE STANDARD HEAD CALIBRATION NOTCH "D" EDGE OF SKIN 17. Inspection of Skin around Skin-to-Spar Attach Fasteners (Area "B") a. Place the same circle template hole (selected in step e. of paragraph 16.) concentrically over the fastener as shown in figure 7. b. Press balance/lift off to balance the instrument, if needed. Adjust Spot XY position, if needed, to bring flying dot into position as shown in figure 6. c. Scan probe around the fasteners while observing the instrument screen. d. Turn MRB over and repeat the preceding steps on the opposite side of the blade. e. Any signal obtained in preceding steps of this paragraph that exhibits a rapid upscale vertical movement equal to or exceeding 50% screen height will be cause for rejection. f. Determine the length or end(s) of the crack by scanning back and forth across the length until the vertical trace returns to the balance point and mark location. Measure and record the location and length of the crack. 18. Reporting a. Report inspection results to: Brantly International Inc., 621 S. Royal Lane Suite 100 Coppell, TX 75019-3805, USA b. Include aircraft S/N, MRB PN., MRB S/N, MRB total time since new, location and length of crack(s) in report. Technique Approved By: Todd L Jackson, Co LIII, JETS, Inc. Date: 11/01/2007 Technique Accepted By: Date: --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. 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