ALERT

TRANSLATION OF

BOLLETTINO TECNICO N° 109S-15

The technical content of this document is approved

under the authority of DOA nr EASA.21J.005.

DATE July 12, 2007

REV. xxxxxxx

Compliance with

this bollettino is:

 ALERT Page 1 of 8

SUBJECT:INSPECTION AND REWORK OF THE LOWER SEMICHANNEL

ASSEMBLIES P/N 109-0642-01-171 OF THE FORWARD FIREWALL.

REASON: Perform an “una tantum” (one time) inspection on the two subject lower 

semi-channel assemblies for the presence of the metallic spacers 

P/N 109-0642-01-195, and if present, perform an inspection on the main 

drive shaft, check the spacers for correct fixation and check the gaskets 

P/N 109-0642-01-169 for correct seating.

HELICOPTERS AFFECTED:

All the Agusta A109S helicopters up to S/N 22034 included, except for 

the S/Ns 22026 and 22033.

COMPLIANCE:

Within the next 20 (twenty) flight hours after the receipt of this Bollettino 

and however within and not later than September 30, 2007.

DESCRIPTION:

Cases of mechanical damage of the main drive shaft 

P/N 109-0415-06-103 have been reported on some A109 series

helicopters.

The resultant investigation identified the reason of the malfunction in the 

missing fixing rivets of the metallic spacers P/N 109-0642-01-195 to the 

lower semichannel assy P/N 109-0642-01-171 of the forward firewall.

The lack of the rivets has allowed the metallic spacers to rotate and 

come into contact with the main drive shaft.

Not all the helicopters are equipped with the metallic spacers 

P/N 109-0642-01-195 on the lower semichannel assy 

P/N 109-0642-01-171, in that the spacers are installed, if required, to 

guarantee a clearance between the main drive shafts and the

semichannels.
B.T. 109S-15

Page 2 of 8

Moreover, during the investigation, cases of wrong positioning of the 

gaskets P/N 109-0642-01-169 have been reported.

This Bollettino provides the instructions to perform an “una tantum” (one 

time) inspection on the two lower semichannel for the presence of the 

metallic spacers.

If installed, it is necessary to perform an inspection on the main drive 

shaft in the semichannels area for damage, correct fixation of the spacer 

on the semichannels and the gaskets for correct seating.

REQUIRED MANPOWER:

An estimated 3 (three) manpower hours are required for compliance with 

this Bollettino.

WARRANTY:

The parts required to apply this Bollettino shall be supplied on a free of 

charge basis, except the consumable materials, by Agusta upon request.

Customers are requested to inform Agusta – Warranty Administration –

by means of the attached Technical Bulletin Compliance Form the

Bollettino implementation.

REQUIRED MATERIALS:

The following materials could be required for compliance with this

Bollettino:

P/N DENOMINATION Q.TY

MS20427M3-5 

or: Rivet 4

MS20426T3-5

A298A04TW02 Rivet 4

In addition the following consumable materials are necessary:

SPECIFICATION DENOMINATION Q.TY

199-05-107 Adhesive EC776 A.R.

Type II Class 5 (cod. 500204274)

TT-M-261 Methylethylketone A.R.

 (cod. 505407211) 

SPECIAL TOOLS: 

N.A.

WEIGHT AND BALANCE CHANGES: 

N.A.

REFERENCES:

A109S Air Vehicle Maintenance Publication.
B.T. 109S-15

Page 3 of 8

PUBLICATIONS AFFECTED: 

A109S Air Vehicle Maintenance Publication.

COMPLIANCE INSTRUCTIONS:

GENERAL NOTES

ÿ Unless otherwise specified retain all

parts that will be removed in following 

operations. Replace damaged

hardware.

ÿ After drilling remove all swarf and sharp 

edges and if required restore the

finishing.

ÿ All dimensions are in mm.

(See figures 1 and 2)

1. Prepare the helicopter on ground for a safe maintenance,

disconnect any power supply.

2. Open the left engine cowling D22 and the right engine cowling 

D28, in accordance with the instructions given in the A109S Air 

Vehicle Maintenance Publication.

NOTE

The following inspection procedure is

applicable for both lower semichannel

assemblies P/N 109-0642-01-171, right

side and left side of the helicopter.

3. With reference to figures 1 and 2, verify if between the lower

semichannel assy P/N 109-0642-01-171 and the door assy 

P/N 109-0642-01-181 and -182 upper semichannel, the two

metallic spacers P/N 109-0642-01-195 are installed (semichannel 

left side and right side). 

NOTE

To verify the metallic spacers 

P/N 109-0642-01-195 presence use a

mirror and a suitable light source.

3.1 If between the lower semichannel and the upper semichannel 

metallic spacers P/N 109-0642-01-195 are not installed, no

corrective action is necessary. Perform Step 6 and subsequent of 

this Bollettino.
B.T. 109S-15

Page 4 of 8

3.2 If between the lower semichannel and the upper semichannel 

metallic spacers P/N 109-0642-01-195 are installed, proceed in 

accordance with Step 4 and subsequent of this Bollettino.

4. Perform the inspection on the main drive shaft, the metallic

spacers for correct fixation on the semichannels and the gaskets 

for correct seating as follows:

4.1 In accordance with figures 1 and 2, from the forward firewall assy 

P/N 109-0642-01-101, acting on the relevant fixing hardware,

remove the lower semichannel assy P/N 109-0642-01-171.

NOTE 1

To facilitate the lower semichannel assy

P/N 109-0642-01-171 removal (helicopter

right side and left side), the removal of the 

left engine cowling D22 and the right engine 

cowling D28, in accordance with the

instructions given in the A109S Air Vehicle 

Maintenance Publication is recommended.

NOTE 2

Take note of the installation position and 

side of the spacers and gaskets on the 

semichannel, in that the parts shall be

reinstalled in their original position.

4.2 If present, remove the fixing rivets of the metallic spacers 

P/N 109-0642-01-195 to the lower semichannel assy 

P/N 109-0642-01-171.

4.3 From the lower semichannel assy P/N 109-0642-01-171 remove 

the gaskets P/N 109-0642-01-169 and the metallic spacers 

P/N 109-0642-01-195.

NOTE 1

During this operation pay particular

attention to avoid spacers and gaskets

damage.

NOTE 2

If two or more stacked gaskets are present, 

they must be retained for reuse.

4.4 Remove the old adhesive from the parts using cheesecloth

moistened in Methylethylketone.
B.T. 109S-15

Page 5 of 8

4.5 If not present, in accordance with figure 2, perform the two Ø 2,5 

mm holes through the metallic spacers P/N 109-0642-01-195 and 

the lower semichannel assy P/N 109-0642-01-171, taking care not 

to protrude stick out the metallic spacer towards the inside of the 

semichannel.

NOTE

If in the metallic spacers the holes are

present, use them as template to drill the

lower semichannel.

4.6 In accordance with figure 2, on the lower semichannel assy 

P/N 109-0642-01-171 install the n. 1+1 metallic spacers 

P/N 109-0642-01-195 using two MS20427M3 rivets or two

MS20426T3 rivets or two rivets P/N A298A04TW02.

CAUTION

Install the spacers on the semichannel in 

the original position and side, as noted at 

step 4.1.

4.7 In accordance with figure 2, on the n. 1+1 metallic spacers 

P/N 109-0642-01-195 bond the n. 1+1 gaskets 

P/N 109-0642-01-169 using adhesive EC776.

CAUTION

If at step 4.3 stacked gaskets have been 

removed, bond them over the metallic 

spacers.

4.8 Inspect the main drive shaft tube in the semichannels area for 

damage (nicks and/or scratches).

NOTE

In case the removal of the main drive shaft 

P/N 109-0415-06-103 shall be necessary

reinstall the lower semichannel assy 

P/N 109-0642-01-171, before to start with the 

removal operations in accordance with the

instructions given in the A109S Air Vehicle

Maintenance Publication.

4.9 In case damages are reported, the main drive shaft shall be 

removed from the helicopter, in accordance with the instructions 

given in the A109S Air Vehicle Maintenance Publication, for the 

damages depth measurement.
B.T. 109S-15

Page 6 of 8

CAUTION

In case the damages depth is above to the 

value reported in the A109S Air Vehicle

Maintenance Publication, remove the shaft

from the service and replace it with one of 

the same P/N.

4.10 If removed, reinstall the main drive shaft on the helicopter, in

accordance with the instructions given in the A109S Air Vehicle 

Maintenance Publication.

4.11. If not already performed, reinstall the lower semichannel assy P/N 

109-0642-01-171 on the forward firewall assy P/N 109-0642-01-

101, using the previously removed fixing hardware. 

4.12. Using a feeler gauge verify that the minimum clearance around the 

main drive shaft and the upper and lower semichannels is not less 

than 4,0 mm. 

CAUTION

If in one or more places the minimum

distance should be less than 4,0 mm

immediately contact the Agusta Customer

Support.

5. If removed, reinstall the left engine cowling D22 and the right

engine cowling D28, in accordance with the instructions given in 

the A109S Air Vehicle Maintenance Publication.

6. Return the helicopter in ready to flight condition.

7. Record compliance of this Bollettino in the helicopter log book.


Note: 

Remarks:

Informazioni: 

Information:

Al fine di gestire le varianti alla configurazione base, in relazione all’emissione del Bollettino Tecnico, preghiamo di voler compilare il presente modulo in tutte le sue parti e spedirlo all’indirizzo sopra indicato. Si ringrazia per la gentile collaborazione data. 

We request your cooperation in filling this form, in order to keep out statistical data relevant to aircraft configuration up-to-date. The form should be filled in all 

its parts and sent to the above address. We thank you beforehand for the information given.

MODULO APPLICAZIONE BOLLETTINO TECNICO

TECHNICAL BULLETIN COMPLIANCE FORM

Data: 

Date:

Numero: 

Number:

Revisione: 

Revision:

Prego spedire a questo indirizzo: 

Please send to the following address: 

AGUSTA S.p.A. 

CUSTOMER SUPPORT 

Via per Tornavento, 15 

21019 Somma Lombardo (VA) - ITALY 

Tel.: +39 0331 711100 

Fax: +39 0331 711397 

Telefono: 

Telephone:

Fax:

Data Applicazione B.T.: 

B.T. Compliance Date:

Denominazione Cliente ed Indirizzo: 

Customer Name and Address:

Modello Elicottero 

Helicopter Model S/N Matricola Tail Number

Ore Totali 

Total Hours

Ore D.U.R. 

T.S.O.