### Service Bulletin

01 February 2011 

# 340–27–100

Page 1 of 8 

### ATA CHAPTER: 27 FLIGHT CONTROLS – ELEVATOR – INSPECTION OF ELEVATOR PUSHRODS AND COMPONENTS Mod No. –

1. PLANNING INFORMATION

A. EFFECTIVITY (1) Aircraft: Aircraft Mfg. Serial No’s SAAB SF340A – 004 thru – 159. Aircraft Mfg. Serial No’s SAAB 340B – 160 thru – 459. (2) Spares: Affected.

B. REASON Field experience has indicated that wear of the elevator pushrod has occurred on some aircraft after extended time in service. The pushrod stiffness has been decreased over time, caused by backlash in between the rod end threads and the pushrod body threads. Although properly installed with lock wire and torque, the locknut has been able to back off within a limited range as allowed by the locking device. This phenomena can result in a limited movement of the lock nut whilst still assembled. The subject pushrod is manufactured by three different vendors although only one of those pushrods is showing the backlash tendency over time and will therefore require replacement. The Failure of the pushrod may be difficult to detect under normal conditions and may therefore only be evident at inspections. Degradation of the pushrod, if left unattended, may lead to a free floating elevator affecting the pitch control authority.

C. DESCRIPTION This Service Bulletin gives instructions for: – Inspection of the RH and LH elevator pushrods – Replacement of affected pushrods – Report to Saab after inspection.

D. COMPLIANCE Mandatory For A/C with 30 000 accumulated flight hours or more, Saab recommends this Service Bulletin to be performed within 6 months from release of first issue of this SB. For A/C within the range of 28 000–30 000 accumulated flight hours, Saab recommends this Service Bulletin to be performed prior to 30 000 flight hours or within 6 months, which will occur latest, from release of first issue of this SB. For A/C with less than 28 000 accumulated flight hours, Saab recommends this Service Bulletin to be performed at a scheduled overhaul before the aircraft reach 30 000 flight hours 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.

### Service Bulletin

01 February 2011 

# 340–27–100

Page 2 of 8 F. MANPOWER Estimated time to complete this Service Bulletin is: 2 persons required.
Total manhours: 4 Elapsed time (hours): 2 Labour cost at operators expense.

G. MATERIAL – COST AND AVAILABILITY Price and availability for required material will be furnished on request. Required material will be available 1 month after receipt of order.

H. TOOLING No special tooling required.

I. WEIGHT AND BALANCE
None.

J. ELECTRICAL LOAD DATA
Not affected.

K. REFERENCES Aircraft Maintenance Manual (AMM) 06–30–00 12–00–00 27–00–00–05 27–31–00–02

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 material for the Service Bulletin is available – The documentation is available (2) Make the aircraft safe for inspection. (a) Apply the electrical power (Ref. AMM 12–00–00). (b) Engage the gust lock (locked position) to secure the full elevator down position when the system is unloaded. (c) On the LH circuit breaker panel 9VU, open, tag and safety the circuit breaker:

### Service Bulletin

01 February 2011 

# 340–27–100

Page 3 of 8 LABEL POS C/B RUDDER/GUST LOCK G–4 1CF (d) Remove the electrical power (Ref. AMM 12–00–00). (e) Put up the warning sign ”DO NOT OPERATE THE FLIGHT CONTROLS” in the flight compartment. (f) Put a suitable platform in position to the RH and LH elevator.

B. INSPECTION REF. FIG. 1. WARNING : BEFORE PROCEEDING WITH MAINTENANCE WORK ON OR NEAR MECHANICAL FLIGHT CONTROLS OR PRIMARY FLIGHT CONTROL SURFACES, ENSURE GROUND SAFETY AND/OR WARNING NOTICES ARE IN CORRECT POSITION TO PREVENT INADVERTENT OPERATION OF CONTROLS. (1) Visually Inspect the RH and LH elevator control pushrod (the pushrod) and locate the part number. (a) If the part number is 12003–33 or R20990, continue with the inspection, refer to step B.(2). (b) If the part number is TDF11755 or if the part number is unrecognizable replace the pushrod, refer to step C. Removal/Installation. (2) Inspection of the RH and LH elevator control pushrod NOTE : To do this inspection two persons are required, one that pushes the elevator and one that inspects the pushrod. (a) Push the elevator down, at the same time visually inspect the pushrod (1), the rod end (3) the nut (5) and the locking device (2). Make sure that there are no individual play between the rod end (3) and the pushrod (1) at the locking device (2). (b) Push the elevator up, at the same time visually inspect the pushrod (1), the rod end (3) the nut (5) and the locking device (2). Make sure that there are no individual play between the rod end (3) and the pushrod (1) at the locking device (2). (c) Make sure that the rod end threads (3) are visible thru the inspection hole in the pushrod (1). (d) Make sure that the nut (5) and the locking device (2) is tightened and proper locked with lock wire (4), Ref. AMM 27–00–00–05. (e) Visually inspect the condition of the elevator push rod and the arm fittings. (f) Repeat step (a) to (e) to the opposite elevator. (3) If the pushrod assembly is correct and fulfills the inspection, go to step D. Job Close–up. (4) If the pushrod assembly is incorrect and not fulfills the inspection, replace the pushrod assembly, refer to step C. Removal/Installation.

C. REMOVAL / INSTALLATION REF. FIG. 2. WARNING : BEFORE PROCEEDING WITH MAINTENANCE WORK ON OR NEAR MECHANICAL FLIGHT CONTROLS OR PRIMARY FLIGHT CONTROL SURFACES, ENSURE GROUND SAFETY AND/OR WARNING NOTICES ARE IN CORRECT POSITION TO PREVENT INADVERTENT OPERATION OF CONTROLS. NOTE : The complete pushrod assembly must be replaced, it is not permitted in any situation to replace only the rod end piece.

### Service Bulletin

01 February 2011 

# 340–27–100

Page 4 of 8 (1) Remove the pushrod. (a) Remove the cotter pin (2) from the nut (3). (b) Remove the nut (3), the washers (4) from the bolt (6). (c) Hold the elevator and carefully remove the bolt (6) and the bushing (5) from the elevator clevis. (d) Remove the lock wire (11) from the bolt (12). (e) Remove the bolt (12), the washer (13) and the shaft cap (14). (f) Remove the cotter pin (18) from the nut (17). (g) Loosen the bolt (15) and the nut (17) to make it possible to slide the arm (16) on the shaft splines. (h) Remove the cotter pin (10) from the nut (9). (i) Remove the pushrod (1). (2) Install the pushrod. (a) Install the pushrod (1) to the arm (16) with the bolt (19), the bushing (7), the washer (8) and the nut (9). (b) Torque the nut (9) to 130 – 180 lbf.in (14.7 – 20.3 Nm) and install the cotter pin (10). (c) Install the arm (16) to the shaft splines, make sure that the index mark on the shaft and on the arm (16) aligns. (d) Install the shaft cap (14), the washer (13) and the bolt (12) to the shaft, torque the bolt (12) to 130 – 180 lbf.in (14.7 – 20.3 Nm). (e) Lock the bolt (12) with lock wire (11). (f) Torque the nut (17) to 60–70 lbf.in (6.78 – 7.91 Nm) and install the cotter pin (18). (g) Lift the elevator and install the pushrod (1) to the elevator clevis with the bolt (6), the bushing (5), the washers (4) and the nut (3). (h) Torque the nut (3) to 60 – 85 lbf.in (7.34 – 9.60 Nm) and install cotter pin (2). (i) Adjust the pushrod, (Ref. AMM 27–31–00–02). (j) Torque and lock the pushrod locking device, (Ref. AMM 27–00–00–05).

D. JOB CLOSE–UP (1) Remove all the tools and equipment from the work area. Make sure the work area is clean. (2) Remove the access platforms. (3) Remove the warning sign ”DO NOT OPERATE THE FLIGHT CONTROLS” from the flight compartment. (a) On the LH circuit breaker panel 9VU, remove the tag and close the circuit breaker:

LABEL POS C/B RUDDER/GUST LOCK G–4 1CF
(4) If the pushrod or any component is replaced, do the Elevator Range of Movement Adjustment, Ref. AMM 27–31–00–02.

### Service Bulletin

01 February 2011 

# 340–27–100

Page 5 of 8 (5) After implementation of this Service Bulletin, fill in the table below and send to: Saab AB Support and Services S–581 88 Linköping Sweden Fax +46 13 18 48 74 E–mail: saab340.techsupport@saabgroup.com

.

A/C Serial N/o Date A/C Flight Hours Remarks (Number of pushrods that have been re–placed etc.)

### Service Bulletin

01 February 2011 

# 340–27–100

Page 6 of 8 3. MATERIAL INFORMATION

A. Material required for modification: NOTE : Material is not required if the inspection of the pushrod is within limits.
Item Part Number Qty Nomenclature Designation Remarks
1 R20990 AR Pushrod – –

B. Removal

Item Part Number Qty Nomenclature Designation Remarks
1 TDF11755 AR Pushrod – 30 000 FH or
more.

C. Local Supply

Item Part Number Qty Nomenclature Designation Remarks
– MS24665–155 AR Cotter Pin – – – MS20995C32 AR Lock Wire CRES, 0.032 in. (0.81 mm) –

### Service Bulletin

01 February 2011 

# 340–27–100

Page 7 of 8 A30879 INSPECTION HOLE 1 2 3

4 5

Elevator Pushrod – Inspection FIG. 1

### Service Bulletin

01 February 2011 

# 340–27–100

Page 8 of 8 A30881 1 2 3
4

6 5

7 8 9 10

11

12 15 16 17 18 19

14 13

Elevator Pushrod – Removal/Installation FIG. 2