~ .s'wm~\~ 

WYTWORNIA SPRZ~TU KOMUNIKACYJNEGO 

,,PZL-SWIDNIK" 

SPOLKA AKCYJNA 

Al. Lotnik6w Polskich 1 

21-045 Swidnik, Poland 

Tel. (+48 81) 468 09 01, 751 20 71 

Fax (+48 81) 468 09 19,751 21 73 

Authorization/Certificate EASA: 

EASA. 21J.114 

The contents of this Bulletin has been approved by 

Transportation Equipment Factory PZL Swidnik S.A. 

under DOANo. EASA. 21J.114. 

TECHNICAL BULLETIN No. BT-37-07-196 

NAME-TYPE/MODEL: PZL W -3A Helicopters I PZL W -3A model 

SERIAL NUMBER: All 

SUBJECT: 1. INSTALLATION OF CHECK VALVES IN THE GROUND 

PRESSURE LINE OF HYDRAULIC SYSTEM 1 AND 2 

SUBSYSTEMS 

2. OPERATION SPECIFICATION UPDATE 

The original Bulletin in Polish language was approved on 

24.04.2007. 

The English translation of the original was approved by the 

Manufacturer under delegated authority of ULC. 

Agnieszka Siedlecka 

GILC-Authorized Interpreter 
I 

This is to inform the PZL W-3A/Model PZL W-3A users that PZL-Swidnik S.A. has designed 

and launched a serial production of the check valves 37.59.336.00.00 intended for installation in the 

ground pressure line of subsystems 1 and 2 of the hydraulic system in accordance with the drawing 

37.59.330.00.00. The valves are used to prevent the hydraulic fluid leakage from both the subsystems 

when any of the hoses installed between the hydraulic blocks and the ground supply board gets 

damaged. 

After the installation of the valves 37.59.336.00.00 on the helicopter, the provisions of the 

Obligatory Bulletin B0-37-07-192 shall cease to be valid. The said Bulletin recommended 

disconnecting the hose 37.59.234.00.00 and the pipe 37.59.233.00.00 installed in the ground pressure 

line of the Subsystems 1 and 2 from the hydraulic block fittings. 

II 

In order to install the valves on the helicopters in operation, remove the pipe 37.59.233.00.00 and 

the hose 37.59.234.00.00 connecting the hydraulic blocks pressure lines with the elbows on the upper 

deck and replace them with the check valves 37.59.336.00.00 and the pipe 37.59.333.00.00 and the 

hose 37.59.334.00.00. 

The valves shall be installed in accordance with Sketch 1 and the following procedure: 

1) Drain the fluid from the reservoirs of both hydraulic blocks as per the Operation Sheet 29.00-2 of the 

Maintenance Manual. 

2) Remove the hoses 37.59.233.00.00 and 37.59.234.00.00. 

3) Install check valves 37.59 .336.00.00. on the hydraulic blocks ground pressure line fittings of the 

Subsystems 1 and 2. Set the valves so the axes of the sockets where the hoses are connected match 

the axes of the hose fittings. 

4) Fit the hose 37.59.334.00.00 (Subsystem 1) and the pipe 37.59.333.00.00 (Subsystem 2) between the 

fittings of the installed check valves and the elbow connectors on the upper deck. 

Follow the procedure laid down in Subchapter 29.00.00 of the Maintenance Manual and the notes 

specified below. 

5) Use clips to fix the hose to the hydraulic block base tubes. 

6) Lockwire the screw joints. 

7) Fill the helicopter hydraulic system with the working fluid as per Operation Sheet 29.00-2, wash the 

system as per Operation Sheet 29.00-4 and check the hydraulic system operation as per Operation 

Sheet 29.00-3. 

Notes: 

1) Keep a proper cleanness while installing the hose and do not perform any activities that may produce 

dust or chips. Seals and plugs of the hoses shall be removed directly before the hoses are connected. 

2) The screw joints shall be screwed together using the hydraulic oil used in the system. 

3) Prior to the installation of the hose, check the following: 

a) Proper placement of the hose (proper shape), 

b) Alignment (degree ofthe axis dislocation) ofthe hose fitting relative to the cone ofthe component 

onto which the hose is to be installed. The axis dislocation when the hose is not fitted shall not 

exceed 0,5d (the hose inner diameter) along 50d from the hose connection point and shall vary in 

proportion to the change in the distance between the hose fitting and the connection point. 

2/6 BT-37-07-196 
c) Alignment of the mating cones of the hose and connector in the connection points. The 

alignment of the cones shall be checked by tightening the hose nut. The nuts should be screwed 

finger-tight easily along 2/3 of the thread length. 

4) To ensure proper alignment of the hose cones with the cones of the parts/products fittings to which 

the hose is connected, it is allowable to fit the hose previously removed from the helicopter by 

bending the pipe smoothly (causing no folds or excess bends) in the curvature area. Over-bending 

the pipe and its deformations within 10 mm from the edge of the fitting are not acceptable. The 

hose section cannot be flattened in the overbend area by more than 15% of its outer diameter. 

III 

List of parts required for accomplishment of this Bulletin 

Item Nomenclature Drawing, Specification, Type Quantity I Notes 

rotor 

1. Hose 37.59.333.00.00 1 

2. Hose 37.59.334.00.00 1 

3. Check valve 37.59.336.00.00 2 

4. Clip 1666s50-8-R 1 

5. Clip 1666s50-16-R 1 

6. Clip 1666s50-18-R 1 

7. Clip 1672s52-8-I-N 1 

8. Screw 3166A-5-10 2 

9. Nut 3373A-5 2 

10. Washer 5,3x8x0,8- 20ZnC BN-7711118-01 2 

11. Lock wire pb- II- Na <!> = 0,8 1= 1m --

IV 

The check valves shall be installed on the helicopters in operation by the User's authorized 

maintenance facility personnel. The installation may also be performed by PZL-Swidnik S.A. as part of 

a separate order of the User and at the User's expense. 

The parts required for the accomplishment of this Bulletin shall be supplied by 

PZL-Swidnik S.A. at the User's request and expense. 

v 

1) Chapter 29 of the W-3A Helicopter Maintenance Manual, Doc. No. AE 30.04.20.1 lOT (in Polish) 

and AE 30.04.20.1 MM (in English) shall be revised to include the provisions of Revision 5 (March 

2007). In order to revise the Chapter, the following pages of the Manual shall be replaced: 

- Page 1 in the List of Effective Pages; 

- Pages 2,4 and 5 in Subchapter 29.00.00; 

- Pages 2 and 4 in Subchapter 29.02.00; 

- Pages 6, 7 ,8,9 in Subchapter 29.1 0.00; 

- Pages 8, 9 in Subchapter 29.12.00. 

BT-37-07-196 3/6 
2) After installing the valves in the helicopter, enter the following statement in the Log Book: 

Check valves 37.59.336.00.00 have been installed in the ground pressure lines 

of the hydraulic system. 

As evidence that the valves installation has been completed, enter the Bulletin reference number 

and the installation date in the Log Book. The record shall be finally confirmed with a stamp and 

signature of the person performing the installation. 

4/6 BT-37-07-196 
Sketch 1. Installation of check valves 

,..KL 

Upper deck plane 

--·---J-~. =+=~~~~~~~~~~ Frame 14 plane ~ 

Hose 37.59.233.00.00 valve installation) 

Hose 37.59.333.00.00 (afire valve installation) 

Hose 37.59.234.00.00 valve· 

Hose 37.59.334.00.00 (after valve installation) 

A B 

1666s50-8-R 

1666s50-16-R 

Washer 5 3x8x0 

BT-37-07-196 ·I 5/6 
Sketch 1. continued 

c 

valve 37.59.336.00.00 

Hose 37.59.334.00.00 Hose 37.59.333.00.00 

6/6 BT-37-07-196