ASB No. AS366-53.11 

Revision 0 2011-05-03. Approved under EASA DOA No. 21J.056. Page 1/35 

Revision 1 2011-09-21 This document is available on the Internet: www.eurocopter.com/techpub

 Civil versions: G1 

 Military versions: Ga 

ALERT SERVICE BULLETIN 

SUBJECT: FUSELAGE

 Draining tank box area 

 Corresponds to modifications 0745C96, 0753C98, 

365A084485.00 

Revision No. Date of issue 

Revision 0 2011-05-03 

Revision 1 2011-09-21 

Summary: 

Modification to draining system of tank boxes. 

For aircraft equipped with emergency buoyancy FP (Fixed Parts), this modification consists of: 

- canceling one drain plug per fuel tank compartment in order to make drain possible (except for center tanks), 

- creating a new drain point for each RH and LH center tank compartment, 

- installing self-sealing drain valves replacing previously-removed drain plugs or on newly-performed drains, in 

order to guarantee compartment sealing in case of ditching. 

For aircraft not equipped with emergency buoyancy FP, this modification consists of: 

- canceling one drain plug per fuel tank compartment in order to make drain possible. 

Reason for last revision: 

- For aircraft equipped with emergency buoyancy FP: 

. propose a new operational procedure to create new drain points without disassembling center tanks. 

- Take into account customer feedback. 

Compliance: 

Compliance with this Alert Service Bulletin is mandatory. 

For the attention of 
 

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1. PLANNING INFORMATION 

 CAUTION

THE INFORMATION AND INSTRUCTIONS IN THIS 

SERVICE BULLETIN ARE INTENDED FOR 

MAINTENANCE PERSONNEL. 

1.A. EFFECTIVITY 

1.A.1. Helicopters/installed equipment

Helicopters: 

- pre-modifications 0753C98 and 0745C96, 

or 

- pre-modification 365A084485.00. 

1.A.2. Non-installed equipment

Not applicable. 

1.B. ASSOCIATED REQUIREMENTS 

Not applicable. 

1.C. REASON 

The purpose of this Alert Service Bulletin Revision 0 was to improve draining of the helicopter tank boxes by: 

- canceling some drain plugs in order to drain tank compartments, 

- installing self-sealing drain valves for aircraft equipped with buoyancy FP. 

The purpose of this Alert Service Bulletin Revision 1 is to: 

- in order to reduce the grounding time, propose for aircraft equipped with emergency buoyancy FP and 

panels under bottom structure (u) (see photo page 12), a new operational procedure to create new drain 

points without disassembling center tanks, 

- take into account customers feedback. 

NOTE

Aircraft not equipped with panels under bottom structure (u) 

must mandatorily disassemble center tanks to create new 

drain points. 

Revision 1 of this Alert Service Bulletin does not question compliance with Revision 0. 

Revision 1 of this Alert Service Bulletin will be subject to EASA Airworthiness Directive. 
 

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1.D. DESCRIPTION

For aircraft equipped with emergency buoyancy FP: 

- remove drain plug located on: 

. front tanks at X3100 / Y570 and Y-570, 

. rear tank at X4920 / Y360, 

- create two new drain points (on the center tanks) at X3207 / Y408 and Y-408, 

- install a self-sealing drain valve on: 

 . front tanks at X3100 / Y570 and Y-570, 

 . center tanks at X3207 / Y408 and Y-408, 

 . rear tank at X4920 / Y360, 

For aircraft not equipped with emergency buoyancy FP: 

- remove drain plug located on: 

. front tanks at X3100 / Y570 and Y-570, 

. center tanks at X3193 / Y576 et Y-576, 

. rear tank at X4920 / Y360, 

1.E. COMPLIANCE

1.E.1. Compliance at the works

1.E.1.a. Helicopters/installed equipment

According to facilities installed or not on the aircraft (emergency buoyancy FP and/or the 6th tank), comply 

with the different paragraphs of Paragraph 3.B. of this Alert Service Bulletin. 

NOTE

Modifications 0753C98 and 0745C96 (if aircraft equipped 

with buoyancy FP) are incorporated in the definition of new 

helicopters delivered from January 01, 2012. This date is 

given for information only, refer to the Individual Inspection 

Log Book (RIC-AMS), the Equipment Log Cards (FM) or the 

aircraft Log Book to identify the actual modification status of 

the aircraft. 

1.E.1.b. Non-installed equipment

Not applicable. 

1.E.2. Compliance in service

1.E.2.a. Helicopters/installed equipment

EUROCOPTER makes mandatory compliance with this Alert Service Bulletin. 

The works must be performed on helicopter by the Operator. 
 

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1.E.2.a.1. Helicopters equipped with emergency buoyancy FP

Apply § 3. except § 3.B.2.b., within 24 months as from receipt of this Alert Service Bulletin, published at 

the date mentioned in page footer. 

1.E.2.a.2. Helicopters not equipped with emergency buoyancy FP

Apply § 3. except § 3.B.2.a., during the next scheduled inspection without exceeding 110 flight hours as 

from receipt of this Alert Service Bulletin, published at the date mentioned in page footer. 

1.E.2.b. Non-installed equipment

 Not applicable. 

1.F. APPROVAL

 Approval of modifications: 

The information or instructions relating to modification 0753C98 was approved on February 09, 2011 under 

the authority of EASA Design Organization Approval No. 21J.056 for civil version helicopters subject to an 

Airworthiness Certificate. 

The information or instructions relating to modification 0745C96 was approved on February 09, 2011 under 

the authority of EASA Design Organization Approval No. 21J.056 for civil version helicopters subject to an 

Airworthiness Certificate. 

The information or instructions relating to modification 365A084485.00 was approved on February 09, 2011 

under the authority of EASA Design Organization Approval No. 21J.056 for civil version helicopters subject to 

an Airworthiness Certificate. 

 Approval of this document: 

The technical information contained in this Alert Service Bulletin Revision 0 was approved on April 29, 2011 

under the authority of EASA Design Organization Approval No. 21J.056 for civil version helicopters subject to 

an Airworthiness Certificate. 

The technical information contained in this Alert Service Bulletin Revision 0 was approved on April 29, 2011 

by the EUROCOPTER Airworthiness Department for export military version helicopters. 

The technical information contained in this Alert Service Bulletin Revision 1 was approved on 

September 20, 2011 under the authority of EASA Design Organization Approval No. 21J.056 for civil 

version helicopters subject to an Airworthiness Certificate. 

The technical information contained in this Alert Service Bulletin Revision 1 was approved on 

September 20, 2011 by the EUROCOPTER Airworthiness Department for export military version 

helicopters. 
 

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1.G. MANPOWER

1.G.1. Manpower (MOD 0753C98 and 0745C96)

1.G.1.a. Manpower with removal of center tanks 

For compliance with this Alert Service Bulletin, EUROCOPTER recommends the following personnel 

qualifications: 

Qualification: 2 Airframe Technicians.

Time for the operations is indicated for reference, for a standard configuration. 

Time for the operations: 

- 80 hours approximately for the Airframe Technicians (polymerization time for sealing mixture excluded). 

Estimated helicopter grounding time: 10 days approximately. 

1.G.1.b. Manpower without removal of center tanks 

For compliance with this Alert Service Bulletin, EUROCOPTER recommends the following personnel 

qualifications: 

Qualification: 2 Airframe Technicians.

Time for the operations is indicated for reference, for a standard configuration. 

Time for the operations: 

- 8 hours approximately for the Airframe Technicians (polymerization time for sealing mixture excluded). 

Estimated helicopter grounding time: 

- 1 day 1⁄2 approximately (polymerization time for sealing mixture excluded). 
 

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1.G.2. Manpower (MOD 365A084485.00)

For compliance with this Alert Service Bulletin, EUROCOPTER recommends the following personnel 

qualifications: 

Qualification: 1 Airframe Technician.

Time for the operations is indicated for reference, for a standard configuration. 

Time for the operations: 

- 1 hour approximately for the Airframe Technician. 

Estimated helicopter grounding time: 1 hour 1⁄2 approximately.

1.H. WEIGHT AND BALANCE

1.H.1. Weight and balance (MOD 0753C98)

 Weight: Weight negligible. 

 Moment: Moment negligible. 

1.H.2. Weight and balance (MOD 0745C96)

 Weight: +0.190 kg. 

 Moment: 

 - Longitudinal moment: +0.86 m.kg. 

 - Lateral moment: +0.01 m.kg. 

1.H.3. Weight and balance (MOD 365A084485.00)

 Weight: Weight negligible. 

 Moment: Moment negligible. 

1.I. EFFECT ON ELECTRICAL LOADS

Not applicable. 
 

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1.J. SOFTWARE MODIFICATION EMBODIMENT RECORD

Not applicable. 

1.K. REFERENCES 

The following documents are required for compliance with this Alert Service Bulletin: 

MET: 05.21.00.603 : SERVICING – Flight-related inspection (VLV) – 10h // 7 days. 

MET: 24.00.00.300 : ELECTRICAL POWER – Instructions.

MET: 28.00.01.300 : FUEL – General instructions.

MET: 28.10.02.403 : STORAGE – STANDARD TANKS – RH center tank: Removal – Installation.

MET: 28.10.02.404 : STORAGE – STANDARD TANKS – LH center tank: Removal – Installation.

MTC: 20.02.05.401 : ASSEMBLY – Assembly with rivets.

MTC: 20.02.06.101 : LOCKING AND BLOCKING OF ASSEMBLIES – General.

MTC: 20.02.06.402 : LOCKING AND BLOCKING OF ASSEMBLIES – Locking with lockwire.

MTC: 20.03.02.406 : GENERAL RIVET REPLACEMENT PRINCIPLES – "CHERRY-MAX" rivets 

 A.S.N.A 0077 and 0078. 

MTC: 20.06.01.101 : BONDING WITH ADHESIVES – General rules for bonding with adhesives.

MTC: 20.06.01.102 : BONDING WITH ADHESIVES – Bonding method.

MTC: 20.06.01.411 : COMPOSITE STRUCTURE REPAIR – BONDING WITH ADHESIVES – 

HYSOL EA 9396. 

MTC: 20.06.04.101 : USE OF MIXTURES – General information on mixtures.

MTC: 20.06.04.303 : USE OF MIXTURES – Casting No. 11 mixture.

MTC: 20.07.02.201 : SAFETY INSTRUCTIONS – Helicopter parked in a hangar. 

MTC: 20.07.03.406 : TECHNICAL INSTRUCTIONS – Instructions applicable when working on an aircraft 

electrical circuit or when energizing aircraft power generating systems on ground. 

MTC: 20.07.03.408 : TECHNICAL INSTRUCTIONS – General principles applicable for visual cleanliness 

and appearance checks on an aircraft after an inspection or a repair. 

1.L. DOCUMENTS AFFECTED 

Document to be updated: 

The modification will be incorporated in the following manuals: IPC and MET.

Document already updated: 

Not applicable. 
 

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1.M. INTERCHANGEABILITY AND MIXABILITY BETWEEN THE PARTS

 Interchangeability: 

Not applicable. 

 Mixability: 

Not applicable. 
 

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2. MATERIAL INFORMATION 

2.A. MATERIAL: PRICE - AVAILABILITY - PROCUREMENT

Kits and/or components will be delivered in special pricing conditions until December 31, 2012. 

EUROCOPTER 

Etablissement de Marignane 

Direction VENTES et Relations Client (ECR) 

13725 MARIGNANE CEDEX 

FRANCE 

NOTE

On the purchase order, please specify the mode of 

transport, the destination and the serial numbers of the 

aircraft to be modified. 

NOTE

For ALERT SERVICE BULLETINS, order by: 

Telex: HELICOP 410 969F 

Fax: +33 (0)4.42.85.99.96. 

2.B. INFORMATION CONCERNING INDUSTRIAL SUPPORT

For any information concerning the modification kits and/or components or assistance, contact the 

EUROCOPTER network's Customer Support Sales Department. 

2.C. MATERIAL REQUIRED FOR EACH HELICOPTER/COMPONENT 

 Kits or components to be ordered for one helicopter or one assembly only if equipped with emergency 

buoyancy FP: 

Components required for aircraft modification. 

Order components listed below according to modifications to be incorporated. 

 Designation Qty New 

P/N It. Old P/N Instruction 

 

1 Drain plug support 2 365A21-4019-20 1 

2 Rivet 5 ASNA0078A401 

(CHERRY-MAX) 

2 

3 Self-sealing drain valve 6 ENCCDM12 3 
 

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 Material to be ordered separately: 

Designation Qty New 

P/N CM It. Old 

P/N Instruction 

 

Lockwire 4 m EN3628-0,8 CM776 4 

 

 Products to be ordered separately: 

As per Work Cards mentioned in this Alert Service Bulletin and list below: 

Designation Qty Product P/N CM It. 

 

Adhesive compound, 1 L container 

(HYSOL EA 9396) 

0.1 kg ECS0010.10 CM616 5 

Sealing mixture 

(Casting No. 11 mixture) 

0.2 kg DHS268-112.20 6 

 Material supplied by the operator: 

Not applicable. 

 Material required for non-installed components: 

Not applicable. 

 Specific tooling: 

As per Work Cards mentioned in this Alert Service Bulletin. 

2.D. MATERIAL TO BE RETURNED 

Not applicable. 
 

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3. ACCOMPLISHMENT INSTRUCTIONS 

3.A. GENERAL 

- Comply with electrical power supply instructions as per MET Work Card 24.00.00.300. 

- Refer to safety instructions as per MTC Work Card 20.07.02.201 to park a helicopter in a hangar. 

- During removal and installation of tanks (§ 3.B.2.b.), comply with general fuel instructions as per MET Work 

Card 28.00.01.300. 

- Use adhesives as per MTC Work Cards 20.06.01.101 and 20.06.01.102. 

- Carry out assemblies by riveting as per MTC Work Card 20.02.05.401. 

- Carry out assemblies by locking as per MTC Work Card 20.02.06.101. 

- During the use of mixtures, be informed of the general information on mixtures as per MTC Work Card 

20.06.04.101. 

3.B. OPERATIONAL PROCEDURE 

3.B.1. Preliminary steps

- Disconnect all electrical supply sources as per MTC Work Card 20.07.03.406. 

- Install suitable access means. 

- Remove and/or open all panels, padding and equipment as required for easy access to different work 

zones. 

3.B.2. Procedures

3.B.2.a. Helicopter equipped with emergency buoyancy FP

3.B.2.a.1. Removal of drain plugs (MOD 0753C98)

As per Figure 1 

 - Remove the 3 drain plugs (b): 

. 1 plug on the front RH tank at X3100 / Y570, 

. 1 plug on the front LH tank at X3100 / Y-570, 

. 1 plug on the rear tank at X4920 / Y360, 

and store them back in the warehouse. 
 

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3.B.2.a.2. Installation of new drain points (MOD 0753C98)

 Two operational procedures for the installation of new drain points are proposed: 

- for aircraft not fitted with panel (u) and symmetrical panel (see Photo below): 

. installation of new drain points with removal of center tanks (§ 3.B.2.a.2.a.), 

- for aircraft fitted with panel (u) and symmetrical panel (see Photo below): 

. installation of new drain points without removal of center tanks (§ 3.B.2.a.2.b.), 

 

NOTE

Panel (u) is located on the RH side of the aircraft (at X3276 / 

Y496), a second panel is symmetrically located on the LH 

side (at X3276 / Y-496). These two panels allow drain plugs 

to be installed without removing center tanks. 

For aircraft equipped with panel (u) and symmetrical panel, the selection of either of these operational 

procedures is left to the operator's initiative. For aircraft not equipped with panel (u) and symmetrical 

panel, removal of center tanks is mandatory. 

Photo: panel under bottom structure

u 
 

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3.B.2.a.2.a. Installation of new drain points with removal of center tanks

Remove the RH and LH center tanks as per MET Work Cards 28.10.02.403 and 28.10.02.404. 

As per Figure 3 

NOTE

The procedure below describes the operations to be 

performed on the RH side of the aircraft. Operations on the 

LH side are symmetrical. 

- Drill 1 through hole (G) (both skins of NIDA) to diameter 18 mm. 

- Counterdrill hole (G) to diameter 22 mm through the first skin of NIDA (outer side). 

- Drill 2 holes (H) to diameter 1.5 mm through the second skin of NIDA (inner side). Both holes will be 

used as filling and vent holes for sealing mixture (6). 

- Drill NIDA to diameter 26 mm. 

- Install drain plug support (1): 

. by means of 2 rivets (2) as per MTC Work Card 20.03.002.406, 

. by interlaying adhesive compound (5) as per MTC Work Card 20.06.01.411. 

- Inject sealing mixture No. 11 (6) through holes (H) and let polymerize as per MTC Work Card 

20.06.04.303. 

- Perform the same operations (see above-mentioned §) on the LH side of the aircraft. 

Install the RH and LH center tanks as per MET Work Cards 28.10.02.403 and 28.10.02.404. 

3.B.2.a.2.b. Installation of new drain points without removal of center tanks

NOTE

The procedure below describes the operations to be 

performed on the RH side of the aircraft. Operations on the 

LH side are symmetrical. 

As per Figure 5 

- Remove blanking plate (u) and retain its attachments (plate on which a drain plug is positioned) 

(Photos A1 and B1). 

According to the aircraft equipment, this plate can hold an antenna; in this case, disconnect the 

antenna connector. 

NOTE

Removal of panel (u) makes it possible to check cleanliness 

of the front tank compartment, during and after the 

modification. 

- Carry out marking/positioning of the new drain plug by taking the dimension (Photo C1): 

. at + 68 ± 2 mm from the theoretical profile of frame at 9°, 

. at Y408. 
 

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 CAUTION

DURING THE PROCEDURE AND PARTICULARLY 

DURING DRILLING OPERATIONS (INTERNAL AND 

EXTERNAL COATINGS), TREPANNING AND BORING, 

MAKE SURE THAT: 

- YOU DO NOT DAMAGE THE DIFFERENT EQUIPMENT 

LOCATED IN THE TANK COMPARTMENT 

(PARTICULARLY THE TANK), 

- THERE IS NO FOREIGN BODY IN THE TANK 

COMPARTMENT (CHIPS, FILINGS, TOOLS, ...), 

- THE FUEL TANK COMPARTMENT IS CLEAN. 

As per Figure 6 

- Inside the tank box, position adhesive tape (aa) on the inner coating of the first drilling (Detail U1 and 

Photo V1). This is to prevent chip projection inside the tank box.

- Drill hole G through (external and internal) coatings to diameter 4.2 mm, by respecting perpendicularity 

of the drilling with respect to (external and internal) coatings (Photo E1). 

- Trepan the external coating to diameter 20 mm (Photo F1). 

As per Figure 7 

- Drill honeycomb to diameter 37 mm, then clean by suction (Photo G1 and detail D1). 

- Trepan the inner coating to diameter 17 mm making sure to machine the coating only without passing 

through adhesive tape (aa) previously positioned. The adhesive tape enables filings to be collected 

during drilling and trepanning, and prevents any filing projection inside the tank box; these filings 

mainly remain trapped in adhesive tape (aa) (Photos H1 and J1, and Detail D1)).

- Remove adhesive tape (aa) and clean the trepanned area (Photo J1). 

As per Figure 8 

- Position drain plug support (1) and point the 2 rivet holes (2) (Photo K1). 

- Drill the 2 rivet holes to diameter 3.2 mm on the external coating and make sure that the honeycomb is 

sufficiently drilled on the 2 holes (Photo K1 and Detail Q1). 

- Make sure that the area is completely cleaned. 

- Bond drain plug support (1) using adhesive compound (5) as per MTC Work Card 20.06.01.411, 

positioning it with "Spincers" (ab) (Photo L1, and Details Q1 and R1). 

As per Figure 9 

- Slowly inject sealing mixture No. 11 (6) through the first rivet hole until it goes out through the periphery 

of hole diameter 17 mm of the inner coating as per MTC Work Card 20.06.04.303 (Photo M1 and 

Detail T1). Rivet firstly drain plug support (1) through the first filling hole by means of a rivet (2) as per 

MTC Work Card 20.03.02.406 (Photo P1, and Details S1 and T1): 

The operation must be carried out by 2 persons (Photos N1 and M1, Detail T1): 

. the first person injects the sealing mixture, 

. the second person checks with mirror (ac) (inside the fuel compartment) until the mixture 

appears at the periphery of drain plug support (1). 

- Clean the excess sealing mixture. 
 

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- Then, inject sealing mixture No. 11 (6) through the second rivet hole. Apply the same procedure as 

before in order to improve the filling (Photo M1). 

- Secondly, rivet drain plug support (1) through the second filling hole with rivet (2) as per MTC Work 

Card 20.03.002.406 (Photo P1, and Details S1 and T1). 

- Clean the excess sealing mixture. 

- Clean the internal and external area and let polymerize. 

As per Figure 5 

- Re-install blanking plate (u) by means of attachments previously retained (Photo A1). If the antenna 

is installed on the plate, reconnect the antenna connector.

Perform the same operations (mentioned in § above) on the LH side of the aircraft. 

3.B.2.a.3. Installation of self-sealing drain valves (MOD 0745C96)

 As per Figure 4 

 - Install 5 valves (3): 

. 1 valve on the front RH tank at X3100 / Y570, 

. 1 valve on the front LH tank at X3100 / Y-570, 

. 1 valve on the RH center tank at X3207 / Y408, 

. 1 valve on the LH center tank at X3207 / Y-408, 

. 1 valve on the rear tank at X4920 / Y360, 

. direct holes (T) of all valves (3) towards the rear of the aircraft, 

. torque to between 1.3 and 1.7 m.daN (115.1 – 150.5 lbf.in), 

. lock all the valves by means of lockwire (4) as per MTC Work Card 20.02.06.402. 

3.B.2.b. Helicopter not equipped with emergency buoyancy FP

Removal of drain plugs (MOD 365A084485.00) as per Figure 2 

- Remove the 5 drain plugs (b): 

. 1 plug on the front RH tank at X3100 / Y-570, 

. 1 plug on the front LH tank at X3100 / Y-570, 

. 1 plug on the RH center tank at X3193 / Y576, 

. 1 plug on the LH center tank at X3193 / Y-576, 

. 1 plug on the rear tank at X4920 / Y360, 

and store them back in the warehouse. 

3.B.3. Tests

Not applicable. 

3.B.4. Final steps

- Remove access means installed in § 3.B.1. 

- Perform a visual cleanliness and appearance check as per MTC Work Card 20.07.03.408. 

- Reconnect all electrical supply sources disconnected in § 3.B.1 as per MTC Work Card 20.07.03.406. 

- Re-install and/or close all the padding, panels and equipment removed and/or opened when restoring the 

aircraft to flight conditions (§ 3.B.1.). 
 

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3.B.5. Ground run-up / flight test

Not applicable. 

3.B.6. Operational procedure on non-installed equipment

Stock retrofitting: 

Not applicable. 

 Stock replacement, stock scrapping and stock building-up: 

Stock building-up of spare parts, in particular self-sealing drain valves P/N ENCCDM12, related to the 

compliance of this Alert Service Bulletin is left to the operator's initiative. 

3.C. IDENTIFICATION 

 Identification of this document: 

Record compliance with this Alert Service Bulletin in the aircraft documents. 

 Identification of modifications in the documents: 

As per incorporated modifications, record compliance with modifications 0753C98 and 0745C96, or 

modification 365A084485.00 in the aircraft documents. 

3.D. OPERATING AND MAINTENANCE INSTRUCTIONS

 Operating instructions: 

Not applicable. 
 

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 Maintenance instructions:

 Refer to MET Work Card 05.21.00.603 and: 

 - as per aircraft version: 

. § 4.2 Station 2 

or 

. § 7 FUSELAGE STRUCTURE LH SIDE 

 

 - Tank compartment and sealed 

compartments under the cabin 

 

 - Existing drain plugs : Open and close. 

 - Self-sealing valves (if installed) : Check each valve for correct operation by 

 actuating the float with the push-button 

 

. § 4.7 Station 7 

or 

. § 4.8 Station 8

or 

. § 11 FUSELAGE STRUCTURE RH SIDE 

 

 - Tank compartment and sealed 

compartments under the cabin 

 

 - Existing drain plugs : Open and close. 

 - Self-sealing valves (if installed) : Check each valve for correct operation by 

actuating the float with the push-button. 

The Maintenance Manual (MET) will incorporate this instruction at the time of a further revision. After 

incorporation of this instruction in the Maintenance Manual (MET), refer to it.
 

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Figure 1 
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Figure 2 
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Figure 3 
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Figure 4 
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Figure 5 
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Figure 6 
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Figure 7 
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Figure 8 
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Figure 9