ALERT 

BOLLETTINO TECNICO N° 139-018 

The technical content of this document is approved

under the authority of DOA nr. EASA.21J.005 DATE October 18, 2006

REV. B 

Compliance with 

this bulletin is: 

ALERT Page 1 of 9

SUBJECT: middle section frame 5700 inspection 

REASON: to verify the structural integrity of the frame – STA 5700 

HELICOPTERS AFFECTED: all AB139/AW139 helicopters except for the prototypes 

(S/N 31002, 31003, 31004 and 31007) 

B 

COMPLIANCE: within and not later 10 flight hours from the issue date of present 

Bollettino and subsequently every 100 flight hours. For helicopter that 

have not yet accumulated 100 flight hours this Bollettino must be applied, 

in the terms above mentioned within 10 f/h and subsequently every 100 

f/h, only when 100 f/h are reached. 

B 

DESCRIPTION: the scope of the inspection is the locating of possible damage and / or 

fatigue failure 

REQUIRED MANPOWER: it is estimated that in order to accomplish this Bollettino 1 

man-hour is necessary. 

WARRANTY: N.A. 
B.T. 139-018 Rev.B 

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REQUIRED MATERIALS: N.A. 

SPECIAL TOOLS: 9 borescope; 

9 drill; 

WEIGHT AND BALANCE CHANGES: N.A. 

REFERENCES: N.A.

PUBLICATIONS AFFETCTED:

9 AW139 Maintenance Planning Information 

COMPLIANCE INSTRUCTIONS:

1. Prepare the helicopter for a safe ground maintenance. Disconnect the battery and all 

the electrical power sources and/or the external power supply. 

2. Remove the cabin liners to get access to the left and right side of upper middle section 

of the fuselage (passenger cabin). 

3. On the helicopters equipped with the inspection panel (as shown on Fig.3 and 4), do a 

detailed inspection of frame 5700 as follows: 

3.1. Remove the screws that attach the inspection panel on the structure, on the left 

side of passenger cabin, (as shown on Fig. 3), to permit the borescope head 

insertion. 

3.2. Do a detailed inspection with the borescope of the frame 5700 with particular 

attention to any evidence of cracks around the area shown on Fig. 5 

3.3. If a photo camera is available, take a picture of any damage found and record 

damage dimensions. Record damage dimensions too in case the photo camera is 

not available. 

3.4. In case you are not sure to have obtained best investigation results (from step 3.1 

to 3.3), do an hole into skin that cover the structure of frame 5700, on the left side 
B.T. 139-0018 Rev.B 

Page 3 of 9 

of passenger cabin, (as shown on Fig. 4). The diameter of the hole, must permit the 

borescope head insertion and shall not exceed 20 mm. (0.7874 Inches). 

CAUTION

To avoid damaging the helicopter structure, do not 

drill through the 5700 frame lip. The frame lip is 50 

mm wide (25/25) see detail A of fig.1 for typical 

inspection holes location. 

3.5. Perform another detailed inspection with the borescope of the frame 5700 with 

particular attention to any evidence of cracks damage around the area shown on 

Fig. 5 

3.6. Take a picture with the photo camera of any damage found and record damage 

dimensions. Record damage dimensions too in case the photo camera is not 

available. 

3.7. Do again the procedures indicated from step 3.1 to step 3.6 on the right side of 

upper middle section of the fuselage (passenger cabin). 

4. On the helicopters with fuselage not equipped of an inspection panel (as shown on 

Fig.1 and 2), do a detailed inspection of frame 5700 as follow: 

4.1. Make an hole into skin that cover the structure of frame 5700, on the left side of 

passenger cabin, (as shown on Fig. 1). The diameter of the hole, must permit the 

borescope head insertion and shall not exceed 20 mm. (0.7874 Inches). 

CAUTION

To avoid damaging the helicopter structure, do not 

drill through the 5700 frame lip. The frame lip is 50 

mm wide (25/25) see detail A of fig.1 for typical 

inspection holes location. 

4.2. Do a detailed inspection with the borescope of the frame 5700 with particular 

attention to any evidence of cracks damage around the area shown on Fig. 5. 
B.T. 139-018 Rev.B 

Page 4 of 9 

4.3. If a photo camera is available, take a picture of any damage found and record 

damage dimensions. Record damage dimensions too in case the photo camera is 

not available. 

4.4. In case you are not sure to have obtained best investigation results (from step 4.1 

to 4.3), make a second hole into skin that cover the structure of frame 5700, on the 

left side of passenger cabin, (as shown on Fig. 2). The diameter of the hole, must 

permit the borescope head insertion and shall not exceed 20 mm. (0.7874 Inches). 

CAUTION

To avoid damaging the helicopter structure, do not 

drill through the 5700 frame lip. The frame lip is 50 

mm wide (25/25) see detail A of fig.1 for typical 

inspection holes location. 

4.5. Perform another detailed inspection with the borescope of the frame 5700 with 

particular attention to any evidence of cracks damage around the area shown on 

Fig. 5. 

4.6. Take a picture with the photo camera of any damage found and record damage 

dimensions. Record damage dimensions too in case the photo camera is not 

available. 

4.7. Do again the procedures as indicated from step 4.1 to step 4.6 on the right side of 

upper middle section of the fuselage (passenger cabin). 

5. If any damage is found, contact the manufacturer for the corrective action definition. 

6. Install the cabin liners on the left and right side of upper middle section of the fuselage 

(passenger cabin). 

7. Return helicopter to flight configuration and record for compliance of this Bollettino. 
B.T. 139-0018 Rev.B 

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Detail A
B.T. 139-018 Rev.B 

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B.T. 139-0018 Rev.B 

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B.T. 139-018 Rev.B 

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B.T. 139-0018 Rev.B 

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