Sikorsky Aircraft Corporation

6900 Main Street P.O. Box 9729 

Stratford, Connecticut 06615-9129 

(203) 386-4000 

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ASB 70-06-29A 

October 11/11 

 DRIVE SYSTEM – S-70/H-60 Intermediate Gearbox (IGB) - One Time Borescope Inspection of 

Section 1. Planning Information

A. Effectivity All S-70 and H-60 models and spares with IGB less than 100 hours of 

 flight time since new or overhaul as of the release date of this ASB.

B. Purpose To perform a one-time inspection to verify output bearing is lubricated for all H60’s and S-70’s.

C. Description An H-60 Intermediate Gearbox (IGB) experienced a fracture of the output shaft 

 that drives the tail rotor. This ASB provides a method to visually inspect the 

 lubrication passages from the oil scupper to the input and output housing using a 

 borescope. 

D. Compliance Compliance is essential. The work outlined herein shall be accomplished prior to next 

flight.

E. Approval Inspection item.

Page 1 of 5 ONE-TIME 

 INSPECTION 

ALERT 

SERVICE BULLETIN
ALERT

SERVICE BULLETIN 

Section 1. Planning Information (Continued)

F. Manpower (Estimated)

 ASB 70-06-29A 

 October 11/11 

Task No. of Men No. of Hours Man-Hours*

Perform Inspection 1 2.0 2.0

Remove/Replace IGB, If Required 1 3.0 3.0

Total Man-Hours 5.0

*Estimate does not include time required to prepare helicopter or return it to flight status. 

G. Weight and Balance 

Not affected. 

H. Electrical Load Data 

Not affected. 

I. Software Load Data 

Not changed. 

J. References 

 None 

 K. Publications Affected 

None 

 L. Attachment 

None 

Section 2. Material Information

A. Basis for Material Data 

Per helicopter.

B. Bill of Material 

 None 

C. Consumable Material

                     None 

Page 2 

 ONE-TIME 

 INSPECTION 
ASB 70-06-29A 

 October 11/11

ALERT

SERVICE BULLETIN

Section 2. Material Information (Continued)

D. Tools Required

 See Appendix I for borescope requirements 

Section 3. Accomplishment Instructions

A. Perform inspection of intermediate gearbox (IGB) output seal as follows: 

(1) Drain oil from IGB per drive system maintenance procedures. 

(2) Remove sight glass per drive system maintenance procedures. 

NOTE: The borescope inspection may be waived if the maintainer elects to 

disassemble the IGB for inspection of the lubrication passages noted in Figure 1.

(3) Using borescope inspect lubrication passages from the oil scupper to input and 

 output housings (see Figure 1 and Figure 2) as follows: 

(a) If there are no obstructions in the oil passages, gearbox is acceptable and 

inspection is complete. Reinstall all parts and service in accordance with 

maintenance procedures. 

(b) If obstructions are observed remove IGB and return to Depot for teardown 

evaluation and disposition. Replace with IGB from spares and service in 

accordance with maintenance procedures (NOTE: Replacement IGB should be 

inspected per this ASB unless the suffix “A” has been added to the S/N). 

(4) Return helicopter to service. 

 B. Record of compliance: 

(1) Make an appropriate logbook entry to show compliance with this ASB. 

(2) Upon compliance with this ASB, notify Sikorsky by completing the attached ALERT 

SERVICE BULLETIN COMPLIANCE RECORD and returning it to Sikorsky Aircraft 

Corporation. 

(3) Add an “A” suffix to the S/N of all IGB’s that have been inspected and complied with 

this ASB. 

Page 3 

ONE-TIME 

INSPECTION
ALERT

SERVICE BULLETIN

 ASB 70-06-29A 

 October 11/11 

IGB Oil Passages To Be Inspected

FIGURE 1

Page 4 

 

 

 

 ONE-TIME 

 INSPECTION
ASB 70-06-29A 

 October 11/11

ALERT

SERVICE BULLETIN

Borescope Inspection Through Sight Glass Port

FIGURE 2

Page 5 ONE-TIME 

 INSPECTION
(860) 998-7565

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ATTENTION: SAS PRODUCT SAFETY MANAGER 

SIKORSKY AEROSPACE SERVICES

Upon COMPLIANCE with the attached ASB, Sikorsky requests your cooperation in 

completing and returning this ENTIRE PAGE by MAIL, FAX, or scan & EMAIL.

 No. 70-06-29A

: DRIVE SYSTEM – S-70/H-60 Intermediate Gearbox (IGB) - One Time Borescope 

Inspection of 
BUSINESS REPLY MAIL

MAILSTOP: S328A

ATTENTION: SAS PRODUCT SAFETY MANAGER 

SIKORSKY AEROSPACE SERVICES

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m
Appendix I Page 1

 ULTRASONIC NONDESTRUCTIVE TESTING/ INSPECTION TECHNIQUE 

Technique Number: VT 8000 Rev Number: 0 Part Number: 

70357-06300-044 Part Name: Intermediate Gearbox Material: 

Magnesium 

Rev Date: N/A 

Approved: 10/08/2011 

Part Preparation: Remove sight glass. Personnel performing this inspection should be thoroughly familiar with the operation of bore 

scopes/video probes. 

Equipment and Materials 

Video probe/bore scope: The inspection probe must have at least two way articulation and a length of 20 inches or more. The probe 

should have removable tips in order to view the area of interest from both 0 degrees and 90 degrees. The shaft of the probe must be 

flexible and the focal length of the tip optics should be between 1-5mm near to 20-50 mm far. The diameter of the probe should be 

5mm or less. 

Note: If the proper bore scope equipment is not available, return the gearbox to depot for evaluation. 

Inspection 

• Place the 90 degree tip on the probe the first few inspections for familiarization. See Figure 2. 

• Evaluate the condition of the passages using the 0 degree optical tip on the bore scope or any combination the inspector 

finds necessary. Insert the scope through the sight glass hole into the IGB. See fig 1. 

• Push the scope into the hole in a downward direction after getting past the floor to wall corner and with a slight twist toward 

the input side housing to assist the probe as it follows the designed flow path into the scupper. See Figure 2. 

• If inserted correctly, the probe will bottom out in the scupper at a depth of 20 inches. See Figure 3. 

• The holes are readilly apparent when using the 90 degree optical tip. See figure 4. 

• If the passages are blocked by a plug they will appear as illustrated in figures 5 and 6 when using a 90 degree optical tip. 

• Passages are blocked by a plug they will also appear as illustrated in figures 7 and 8 when using a 0 degree optical tip. 

• Passages that are clear of plugs will appear as illustrated in figures 9 and 10 when using a 0 degree optical tip. 

Reporting 

Note: The plugs are white and difficult to see. If there is any doubt as to the condition of the oil passages route the IGB to the Depot 

for evaluation. If a plugged passage is detected during this inspection red tag the aircraft and R&R the IGB. 
Appendix I

Figure 1

Insert the bore scope into the sight glass hole

Figure 2

Allow the bore scope to follow the natural path into the scupper

Note: Gearbox

shown open

for clarification

purposes

Page 2
Appendix I

Figure 3

If inserted correctly, the probe will stop inside the scupper at a depth of 20 inches.

Figure 4

Both passages in view using 90 degree tip

Note: Gearbox

shown open

for clarification

purposes

Page 3
Appendix I

Figure 5

Plugged input side hole 90 degree tip

Figure 6

Plugged output side hole 90 degree tip

Page 4
Appendix I

Figure 7

Plugged output side hole 0 degree tip

Figure 8

Plugged Input side hole 0 degree tip

Page 5
Appendix I

Figure 9

Input hole clear 0 degree

  

Figure 10

Output hole clear 0 degree  

Page 6