# Service Bulletin

18 November 2009

Revision 01, 05 November 2010 

# 2000–29–024

Page 1 of 13 

# ATA CHAPTER: 29 HYDRAULIC POWER – MAIN HYDRAULIC SYSTEM – INTRODUCTION OF NEW HYDRAULIC ACCUMULATORS
Mod No. 6355

1. PLANNING INFORMATION

A. EFFECTIVITY (1) Aircraft: Aircraft Mfg. Serial No’s SAAB 2000 – 004 thru – 063. (2) Spares: Not affected.

B. REASON Three cases of severe failure have occurred with the existing type of accumulator in other aircraft types. Any of the end parts on the existing accumulator may depart from the pressure vessel if they are affected by corrosion. An end part failure may cause debris to pass out through the aircraft and result in a hazardous situation for both personnel and aircraft. In addition, a qualification issue during the change of the base material, for the end parts of the accumulator back in 1993, can have affected the life limit of the accumulator. This service bulletin introduces a new type of hydraulic accumulator which is made of stainless steel. Implementation of this Service Bulletin will minimize the risks for corrosion and fatigue failures as well as the need for a life limit on the accumulator.

C. DESCRIPTION This Service Bulletin gives instructions for: – Removal of the hydraulic accumulators – Modification of the structure in the nose landing–gear bay – Installation of the new hydraulic accumulators. NOTE : It is not necessary to replace all hydraulic accumulators at the same time. To consider this Service Bulletin as complete all hydraulic accumulators must have been replaced.

D. COMPLIANCE Mandatory. Saab recommends this Service Bulletin to be performed within 12 months from release of first issue of this SB. This Service Bulletin is under EASA consideration for an Airworthiness Directive (AD). The final compliance terms will be set by the EASA Airworthiness Directive when issued.

E. APPROVAL The technical content of this Service Bulletin is approved under the authority of DOA nr. EASA.21J.066.

F. MANPOWER Estimated time to complete this Service Bulletin is:

# Service Bulletin

18 November 2009

Revision 01, 05 November 2010 

# 2000–29–024

Page 2 of 13 2 persons required.

Total manhours: 12 Elapsed time (hours): 6 Labour cost at operators expense.

G. MATERIAL – COST AND AVAILABILITY Price and availability for Mod Kit. No. SAAB 2000–29–024–01 will be furnished on request.

H. TOOLING No special tooling required.

I. WEIGHT AND BALANCE Replacement of all five accumulators:

Weight change + 1.11 kg / +2.45 lb Center of gravity STA 488.4 Change moment + 5.42 kg in / + 11.96 lb in 100

Replacement of one hydraulic accumulator at STA 141.0:

Weight change + 0.22 kg / +0.49 lb Center of gravity STA 141.0 Change moment + 0.31 kg in / + 0.69 lb in 100

Replacement of one hydraulic accumulator at STA 665.2:

Weight change + 0.22 kg / +0.49 lb Center of gravity STA 665.2 Change moment + 1.48 kg in / + 3.26 lb in 100

Replacement of one hydraulic accumulator at STA 747.4:

Weight change + 0.22 kg / +0.49 lb Center of gravity STA 747.4 Change moment + 1.66 kg in / + 3.66 lb in 100

J. ELECTRICAL LOAD DATA

Not affected.

# Service Bulletin

18 November 2009

Revision 01, 05 November 2010 

# 2000–29–024

Page 3 of 13 K. REFERENCES
Aircraft Maintenance Manual (AMM) 29–11–50–000–801
29–11–50–000–802 29–11–50–400–801 29–11–50–400–802 29–11–53–000–801 29–11–53–400–801 29–12–50–000–801 29–12–50–400–801 29–12–50–000–802 29–12–50–400–802 29–12–53–000–801 29–12–53–400–801 Structural Repair Manual 52–20–43

L. OTHER PUBLICATIONS AFFECTED
Aircraft Maintenance Manual (AMM) Illustrated Parts Catalog (IPC)

2. ACCOMPLISHMENT INSTRUCTIONS

A. JOB SET–UP (1) Before you start the SB, make sure: – The modification kit contains the parts listed in the Service Bulletin – The documentation is available. (2) Make the hydraulic systems safe for maintenance, Ref AMM TASK 29–10–00–860–802.

B. REMOVAL (1) Remove the hydraulic accumulators from the hydraulic compartment on the right hand side of the nose landing–gear bay (a) Remove the accumulator for the number 1 system, ref. AMM TASK 29–11–50–000–801. (b) Remove the accumulator for the number 2 system, ref. AMM TASK 29–12–50–000–801. (2) Remove the accumulators from the wing to fuselage fairing. (a) Remove the accumulator for the number 1 system, ref. AMM TASK 29–11–50–000–802. (b) Remove the two accumulators for the number 2 system, ref. AMM TASK 29–12–50–000–802.

# Service Bulletin

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# 2000–29–024

Page 4 of 13 C. MODIFICATION
WARNING : BE CAREFUL WHEN YOU USE THE CONSUMABLE MATERIAL(S). YOU MUST OBEY THE OPERATOR’S AND MANUFACTURER’S HEALTH AND SAFETY INSTRUCTIONS. THE CONSUMABLE MATERIAL (S) CAN CAUSE INJURY OR DEATH TO PERSONS. (1) Prepare the new accumulators for installation
REF. FIG. 1 (a) Move the charging valves and the new accumulators

1 Remove the charging valves (7) from the accumulators in the number 1 system, ref. AMM TASK 29–11–53–000–801.

2 Remove the charging valves (7) from the accumulators in the number 2 system, ref. AMM TASK 29–12–53–000–801.

3 Install the extension bosses on the new accumulators

a Apply a thin layer of the corrosion protection (Tef–Gel) on the threads of the extension bosses (5).

b Install the packing (4) and the extension boss (5) to the new accumulator (3).

c Use a torque wrench and torque the extension boss to between 6.77 and 9.04 Nm (60 and 90 lbf. in.).

4 Apply a thin layer of the corrosion protection (Tef–Gel) on the threads of the charging valves (7).

5 Install the charging valves (7) to the new accumulators in the number 1 system, ref. AMM TASK 29–11–53–400–801.

6 Install the charging valves (7) to the two new accumulators in the number 2 system, ref. AMM TASK 29–12–53–400–801.

7 Use the lockwire (9) and safety the charging valves (7) to the accumulators. (b) Move the reducers to the new accumulators
NOTE : The procedure for one reducer (1) is described. The procedure is the same for all.

1 Remove the reducer (1) and the packing (2) from the accumulator (3). Discard the packing (2).

2 Apply a thin layer of the corrosion protection (Tef–Gel) on the threads of the reducer (1).

3 Install the new packing (2) together with the reducer (1) to the accumulator (3).

4 Use a torque wrench and torque the reducer (1) to between 31.7 and 34.5 Nm ( 280 and 305 lbf.in). (2) Remove the protection pads from the structure
REF. FIG. 2 (a) Carefully remove the pads (1) from the structure brackets that hold the accumulators.
NOTE : There are totally 10 pads installed, four in the nose landing–gear bay and six in the fuselage fairing area. (b) Use MEK and a suitable non–metallic scraper and remove the old adhesive from the brackets.

# Service Bulletin

18 November 2009

Revision 01, 05 November 2010 

# 2000–29–024

Page 5 of 13 (3) Do the structure modification (first stage) for the aft accumulator in the nose landing–gear bay
REF. FIG. 3 (a) Put a suitable protection sheet and cover the area below the attachments brackets for the accumulators. (b) Use a suitable tool and remove material from the bracket (1). If required, remove material from the bracket (2). Make sure the edge distance is minimum 6 mm (0.24 in). (c) Temporary install the accumulator and measure the clearance between the charging valve and the structure.
1 If the clearance is less than 6.35 mm (0.24 in), remove the accumulator and do the structure modification (second stage), refer to para (4).

2 If the clearance is more than 6.35 mm (0.24 in):

a Remove the accumulator and apply surface protection to the bare metal (Refer to SRM 50–20–43).
b Remove the protection material and clean the area. continue with the installation, para D. (4) Do the structure modification (second stage)
REF. FIG. 4 (a) Remove the four rivets (BJ–5) from the angle (R2). Remove and discard the angle (R2). (b) Make a new angle (4)
1 Use the flat pattern view (REF. FIG. 4, sheet 2 of 2) as a template.

2 Measure and make sure the dimensions of the template are correct.
3 Make the new angle (4).
4 Apply surface protection (Refer to SRM 50–20–43). (c) Cut the bracket (1) as shown in view C–C. Apply surface protection (Refer to SRM 50–20–43). (d) Put the new angle (4) in position and transfer the holes for the rivets (BJ–5) (3plcs). (e) Mark out and drill a hole for the new BJ–5 rivet. (f) Remove the angle (4) and deburr the holes. (g) Put the angle (4) in position and install the rivets (BJ–5–5) (4 plcs). (h) Remove the protection material and clean the area. Continue with the installation, para D.

D. INSTALLATION (1) Install the hydraulic accumulators in the hydraulic compartment on the right hand side of the nose landing–gear bay (a) Install the new accumulator (3) for the number 1 system, ref. AMM TASK 29–11–50–400–801. (b) Install the new accumulator (3) for the number 2 system, ref. AMM TASK 29–12–50–400–801. (2) Install the accumulators in the wing to fuselage fairing. (a) Install the new accumulator (3) for the number 1 system, ref. AMM TASK 29–11–50–400–802. (b) Install the two new accumulators (3) for the number 2 system, ref. AMM TASK 29–12–50–400–802.

# Service Bulletin

18 November 2009

Revision 01, 05 November 2010 

# 2000–29–024

Page 6 of 13 (3) Check and make sure that there is a minimum clearance of 3 mm (0.12 in.) between the accumulators and adjacent components or structure.

E. JOB CLOSE–UP (1) Remove all tools and equipment from the work area. Make sure the work area is clean.

3. MATERIAL INFORMATION

A. Parts required for modification:

Item Part Number Qty Nomenclature Designation Remarks Fig 1–2 MS28778–8 5 Packing Reducer (1) –Fig 1–3 40800–2050 5 Hydraulic Accumulator – 9309870–001

Fig 1–4 Fig 1–6 MS28778–5 10 Packing Charging valve(7) and extension boss (5) –

Fig 1–5 7229105–165 5 Extension Boss – –
– MS20470AD–5–5 4 Rivet – BJ–5

B. Local supply

Item Part Number Qty Nomenclature Designation Remarks Fig 1–9 MS20995C32 A/R Lockwire – CRES, 0.81 mm(0.032 in) diameter– Tef–Gel A/R Corrosion Protection – Ultra Safety systems Inc., USA Fig 4–4 – 1 Angle, locally manufactured – Aluminium 2024–T3, t=1.27 mm (0.05in)

C. Removal

Item Part Number Qty Nomenclature Designation Remarks– 08 8423 030 1 5 Hydraulic Accumulator – –

Fig 2–R1 7253624–173 10 Pad – Remove and discard

# Service Bulletin

18 November 2009

Revision 01, 05 November 2010 

# 2000–29–024

Page 7 of 13 1

3

4

5

6

7 A

A 2

A A

B18276 

## 7 NOTE:THE CHARGING VALVES ARE NOT THE SAME FOR ALL ACCUMULATORS. MAKE SURE YOU INSTALL THE CORRECT CHARGING VALVE. VIEW A – A TYPICAL B B 3 REF 8 9

TO REDUCER (1) AND CHARGING VALVE (7)

VIEW B – B TYPICAL 9 REF

8 REF

3 REF



# Hydraulic Accumulator – Installation of Reducer, Extension Boss and Charging Valve FIG. 1

# Service Bulletin

18 November 2009

Revision 01, 05 November 2010 

# 2000–29–024

Page 8 of 13 R1 (TYPICAL 10 PLCS)



# A – A

A

A

B18412 

## NOTE:ONLY THE PADS IN THE NOSE LANDING–GEAR BAY SHOWN



# Modification – Removal of Pads FIG. 2Service Bulletin18 November 2009Revision 01, 05 November 20102000–29–024Page 9/10 of 13MIN EDGE DISTANCE6 mm (0.24 in)1 REF2 REFAREA TO BE TRIMMEDMINIMUM CLEARANCE3.0 mm (0.12 in) BETWEENACCUMULATOR ANDSTRUCTUREB – BB18360B12 3STA129VIEW ABAHudraulic Accumlator Installation – Check of and Corrective Action for Clearance (first stage)FIG. 3

# Service Bulletin

Date Month Year

Revison X, Date Month Year 

# 2000–XX–XXX

Page 10Service Bulletin18 November 2009Revision 01, 05 November 20102000–29–024Page 11/12 of 131R2REMOVE AND SCRAPB18413CUT–LINE: CUT 1 AND 4TO FIT WITH NEWACCUMULATOR.MINIMUM CLEARANCE3 mm (0.12 in) BETWEENACCUMULATOR ANDSTRUCTURE14 REF4LEAVE HOLE OPENIN ITEM 11R2 REFCorrective Action (second stage)FIG. 4 (Sheet 1 of 2)

# Service Bulletin

Date Month Year

Revison X, Date Month Year 

# 2000–XX–XXX

Page 12

# Service Bulletin

18 November 2009

Revision 01, 05 November 2010 

# 2000–29–024

Page 13 of 13 FLANGE LENGTH 42.5 mm DOWN

40.0 mm 28.0 mm MIN R5

B18415 

# ITEM 4 ISO VIEW

MATERIAL: AL2024–T3 t = 1.27 mm (0.05 in)

Corrective Action (second stage) FIG. 4 (Sheet 2 of 2)