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:
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18 November 2009

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2000–29–024

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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.
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18 November 2009

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2000–29–024

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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.
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18 November 2009

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2000–29–024

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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.
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18 November 2009

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2000–29–024

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(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.
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2000–29–024

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(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
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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
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2000–29–024

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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. 2
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2000–29–024

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AREA TO BE TRIMMEDMINIMUM CLEARANCE3.0 mm (0.12 in) BETWEENACCUMULATOR ANDSTRUCTURE

B18360

B

1

2 3

STA

129

VIEW A

B

A

Hudraulic 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 10
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1

R2REMOVE AND SCRAP

B18413

LEAVE HOLE OPENIN ITEM 1

1

R2 REF

Corrective Action (second stage)

FIG. 4 (Sheet 1 of 2)
Service Bulletin

Date Month Year

Revison X, Date Month Year

2000–XX–XXX

Page 12
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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)