TIME OF COMPLIANCE: See below. 

FAA APPROVAL: To be submitted to the FAA for approval 

Intt·oduction 

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 aU B2 series main rotor· blades are considered unairn•orthy and are cause 

for blade replacement. Ser·vice 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 senrice bulletin supersedes all other sen ,ice 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shown b I e ow shows each superseded and canceled sections and documents. 

Document Name Revision Section Status 

Br·antly 82 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 Manual March 1963 1.8. 1 a,b,c,d,e,f,g,h, & Fig 2, Superseded!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 Manual May 15,1991 1.8.1 a,b,c,d,e,f, & Fig 11, Pg Superseded/ Canceled 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Brantly Service Letter 110 - Oct 31,2005 All Superseded!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 sen •ice 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 PIN 248-101 and 248-202, before further flight, comply with sections 1 and 2 of 

this service bulletin. Thereafter at inten ·als not to exceed 300 flight hours or 5 calendar years, whichever 

occurs first comply with section 1 and at inten 'als not to exceed 25 flight hours comply with section 2. Also 

comply section 3 of this sen , ice bulletin befor·e the first flight of each day. 

For Outboard Main Rotor Blades PIN 248-404 with less than 10 years time in sen,ice or 1000 flight hour-s, 

com ply with section 3 of this service bulletin before the fir·st flight of each day. 
inter vals 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 (scrvice@br·antly.com) 

Brantly International Inc. 

621 S. Royal Lane; Suite 100 

Coppell, TX 75019-3805 

USA 

Phone 972.829.4600 

I C r ack Ins pection (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 boles 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 boles must be removed from service. If any of these 

defects arc found, remove the blade from service and replace with an airworthy part. Record the results in 

section 4 of this service bulletin. 

2 Delamination Inspections (25 Hour Inspection) 

2.I 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 JOX 

magnifying glass to inspect for· cracks in the main rotor blade. Pay particular· attention to areas amund 

rivet holes, the blade root area, and the trailing edge. 

2.2 No cr-acks or nicks are permitted. No creases, wrinkles or bends are permitted in the trailing edge of the 

blades. Verify adequate edge distance between boles such that no additiona l holes have been added or 

extra rivets used to fill stop drilled boles in the r·oot 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 arc found, remove the blade from service and replace with an ainvorthy 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 ar·e bonded. Pay particular 

attention to the inboard I2 inches (.304m) on the top and bottom. Mark all delaminated areas with a 

grease pencil or cha lk. 

Delaminated areas will have a duller, low pitched sound when compared to areas that are not delaminated. The ' rna • also have as on y or loose feelin when ressed 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 IO in2 (.254m2). Record the results in section 4. 
3 Daily Inspections 

3.1 Before the first flight of each day, visually inspect the outboard main rotor blade for cracks and wrinlding of 

the skin. Pay particular attention to the blade root area, the area around the lead/lag damper mounting fork, 

and the blade trailing edge. 

3.2 No cracks, nicks, or wrinlding 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. 
information given in this service bulletin. Describe the cracks and delamination as much as possible and use the 

figure to create a sl<etcb of their locations. 

H e r acopter I n r. ormation 

Re2. # 

Name 

Tel. 

Serial# TTIS 

Address 

E-mail 

BladeTTIS ~ 2 n (. J J 4 0 r- ; -

No Delamination 

:Permitted In This 

Area 

Results/ Oesca-iptian ofCucks and Delamination 

Date 

Blade TT @ Installation ~ Bonded Area 
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 20 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 

NOT (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 

29982 Ivy Glenn Drive 

Laguna Niguel, CA 92677-2004 

or 

Furon-CHR Division 

407 East Street 

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 NOT (formerly NOT 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 20): 

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) 

(1) GAIN XY1 set to 30.0/45.0 

(2) PHASE 1 • set to 0 

(2) FREQ1 kHz set to 200 kHz 

(3) Filter set to BP LOCK. 

(4) HP/LP filters set to DC/30.0. 

(5) INPUT GAIN1 set to High. 

(6) PROBE1 set to Absolute. 

(OUTPUT) 

(1) ANALOG 0/P 1 set to X1 . 

(2) ANALOG 0/P 2 set to X1 . 

(ALARM) 

Optional 

(TRACE DISP) 

(1) DISPLAY set to Spot. 

(2) GRATICULLE set to Grid 2. 

(3) SPOT XY set to 115/-30. 

(4) SPOT INFO set to None. 

(5) PERSIST set to 5.0 s. 

(6) SWEEP set to 5.0 s. 

(MEMORY) 

See Note 1 

(PROBE) 

MODE set to Normal Single. 

PROBE ID N/A, Unknown. 

LOAD JJH set to 120 or balance hold. 

DRIVE dB set to +8 

BALICLR MOD set to Single. 
gure 1

Calibration Standard ET002 Details 

j 300" ~ .125" 

.30" + ... . 50"+!+ .50" ~l+- 50 !+- 50 -+ ... 50"-

~~ FLAG NOTES 

T MACHINED OUT OF .125" 2024- 0 1 T3 ALUMINUM PLATE. :r: 100° COUNTER SINK ALL 1.00" (.) 1- FASTENER LOCATIONS 

020"4 

0 

. 130" EXCEPT LOCATIONS 5 . /z _j_ FABRICATE FROM .016" THICK MAX. ~' ~~ ~~ ~~ ~~ -.-- 2 2024-T3 CLAD ALUMINUM ~ SHEET. 100° DIMPLE 

~-

t COUNTER SINK ALL EXCEPT 

.980" ~ ~CHr 3.00" FASTENER LOCATIONS 5. MIN. MS20426-AD3 RIVETS (3/32" 

/ 

3 DIAMETER). MAKE SHOP ~ NOTCH B NOTCH ~ HEADS% D X 2 D STANDARD. \, 2.00" MS20426-AD4 RIVETS (1 /8" 50" 

{' f.\ f.'\.~_/.\ ~~ {' 

4 DIAMETER). MAKE SHOP •• j HEADS% D X 2 D STANDARD. 

.st .. J{--' ~,lf'-.-1 \./ 01"\._ 5 STACK DRILL .200" DIAMETER AND DEBUR. 

_l_ 4 4 4 ET002 -XXX 

~ 

VIBRO-ETCH OR ELECTRO1 ..... 60"--. ._ .80"_. 

.3o· l.- <1)/*016" 

6 ETCH PART NUMBER AND 

l+-.50"-+ + .50"-+ SERIAL NUMBER INTO TOP 

--+ .300" ..... __. .109" SURFACE. 

NOTCH DIMENSIONS (INCHES) 

NOTCH LENGTH WIDTH DEPTH 

A .200" MEASURED (.035" FROM EDGE OF COUNTER SINK DIMPLE) .010" MAXIMUM THROUGH 

B EDGE OF FASTENER HOLE TO EDGE OF FASTENER HOLE .010" MAXIMUM THROUGH 

c 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) 

x .xxx = +/- 0.005 

X.XX = +/- 0.025 

x .x = +/- 0.050 

ANGLES: +/- 1.0 DEGREE 

SURFACE ROUGHNESS = 63 Ra OR BETTER 
SKIN-TO-HINGE BLOCK 

FASTENER A REA "A" 

(SEE FIGURE 3) 

BLADE ROOT ~ BLADE T IP 

Figure 3: Fastener Identification and Corresponding Probe Calibration Positions on ET002 ~ SCAN PATTERN ~ ~ USING PROBE GUIDE 

\:;:::/ (SEE FIGURE 5) 

• PROBE 

POSITION 

SKIN EDGE LINE 

AREA "B" FASTENERS 

PROBE 

POSITION 8 

PROBE 

POSITION 2 

0 0 0 

PROBE POSITION 1 

ee 

91NSUFFICIENTIL Y SPACED <D(D ,' AREA "A" FASTENERS 

FASTENERS, AREA "A", 6d),' SEE PAR. 12 AND 13 

<l)SUFFICIENTL Y SPACED ,' KNOWN LOCATIONS OF 

FASTENERS, AREA "A", I SKIN CRACKS EMANATING 

SEE PAR. 14 AND 15 1 FROM FASTENERS 

0 SKIN-TO-SPAR FASTENERS e: LOCATED IN AREA "A" 

I 

AREA "B", SEE PAR. 16 AND 17 t..:·;..;;;-'------------' 

PROBE 

POSITION 4 

PROBE 

POSITION 5 

@ NOTCH 8 

t 

10. Instrument Calibration for Inspection of Skin around Dampener Attach Hole (Area " A") 

PROBE 

POSITION 6 

@NOTCH 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. 

TRAILING 

EDGE 

PROBE 

POSITION 9 

@NOTCH D 

PROBE 

POSITION 7 

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 figu re 4. Adjust the instrument gain to obtain an 80% screen 

height vertical movement from the notch. 
THAN 1-2 DIVISIONS VERTICALLY OR ! ! ! ! ! ! ! 1 ! ! i 1 ! : 1 ! 

HORIZONTAL Y FROM BALANCE POINT ... , ...... , ...... ~··· ··· ··· ·:- ······ ··· : : ···.····-:-····· ··· ···- --1 --·+·····~ ...... ~.ft • • •• DURING SCAN OVER DEFECT FREE AREA i 1 i i 1 ! 

.••· ' ''! ''' ''''! ·····!······:···"'!'"''"' ''''''!''"'''!······:······•!••" .. !''"'"! ''"''!'' 

HORIZONTAL (X) DIVISION LINES 

Figure 5: Proper Circle Selection for Probe Guide 

CIRCULAR SCAN PATTERN 

MICRO TIP PROBE 11 MICRO TIP PROBE FASTENER HEAD 

CALIBRATION NOTCH "A" CALIBRATION NOTCH "C" 

11 . Inspection of Skin around Dampener Attach Hole (Area "A") 

CIRCLE TEMPLATE USED 

AS A PROBE GUIDE 

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. 
p

co

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 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 

"A". 

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 
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 Adj acent 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. 
THE FLYING DOT SHOULD NOT MOVE MORE ···[······[······r······[···· .. ; LIFT-OFF LINE , .. y .· ..... l/; ; ; ; ; ·j .. ; , ; 

 

 

 · . FLYING DOT . 

THAN 1-2 DIVISIONS VERTICALLY OR 20% ; . ; . ; ; --"'i. ; ; ; /I[ ' ' ' ' ' ' 

HORIZONTAL Y FROM BALANCE POINT j l i i i i [ : i ., ... 

DURING SCAN OVER DEFECT FREE AREA l L ! L . .... ! 1 I l I LJ : : : 

HORIZONTAL (X) DIVISION LINES_/..v---

Figure 7: Scan Technique around Area "B" Fasteners 

CIRCULAR SCAN PATTERN 

I I MICRO TIP PROBE I I ET002 l CIRCLE TEMPLATE USED 

CALIBRATION FASTENER AS A PROBE GUIDE 

STANDARD \ 

CALl BRA TION 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 Llll, JETS, Inc. Date: 11/01/2007 

Technique Accepted By: Date: