SIL 01-10

Page 1 of 3Jul 29/10

KIDDE GRAVINER LIMITED

Mathisen Way

Colnbrook, Slough, SL3 0HB, England

Telephone: +44 (0)1753 683 245

Fax: +44 (0)1753 685 040

CAGE K1536

SERVICE INFORMATION LETTER (SIL) 01-10

AUTOMATIC FIRE EXTINGUISHERS WITH SINGLE OPERATING HEAD 

Cases have occurred where excess solder has been used during the soldering process on single head automatic

fire extinguishers. This has occurred during the soldering process of the operating head and container and has

caused an extinguisher to fail to discharge on operation of the aircraft firing handle. 

During maintenance when the operating head is removed from the container an examination is to be carried out of

the frangible plug in the operating head (refer to Figure 1 and 2) for any deposits of solder. Solder deposits are to

be reported immediately to the CAA by email at this address:

Ian.Chrimes@caa.co.uk

These Automatic Extinguisher Part Numbers part numbers are affected:

12A, 13A, 59A, 60A, 99A, 146A, 161A, 162A, 167A, 170A, 170A-02, 182A, 187A, 229A(1), 242A(1), 236A,

237A, 241A, 1167A, 1187A, 1200A, 57133 SERIES, 57135 SERIES, 57183 SERIES, 57331 SERIES,

57333 SERIES, 57335 SERIES, 57183 SERIES.

Should you require further technical information, contact Tony Carroll, Aircraft Technical Support Manager

Tony.Carroll@hs.utc.com or fax +44 (0)1753 685040.

This Service Information Letter highlights the clarifications of excessive tinning / soldering procedure to control the

risk of excess solder migrating to the frangible plug area of the head.

© KIDDE GRAVINER LIMITED 2010 

The information contained in this SIL is the property of KIDDE GRAVINER LIMITED and may not be reproduced or transmitted in any form

or by any means, electronic, mechanical, photocopying, recording or otherwise, nor stored in any retrieval system of any nature without the

express written authority of KIDDE GRAVINER LIMITED.
SERVICE INFORMATION LETTER

SIL 01-10

Page 2 of 3

Jul 29/10

8

SECTION THROUGH THE HEAD SHOWING HOW THE 

EXCESS SOLDER HAS FORMED A FILLET ON TOP OF THE 

FRANGIBLE DIAPHRAGM RENDERING IT INOPERATIVE

Frangible 

Solder Fillet Diaphragm

Figure 1 

Correct tinning of the threads without excessive amounts of solder contained in the threads or around the 

frangible diaphragm

Figure 2 

Section through the head
SERVICE INFORMATION LETTER

SIL 01-10

Page 3 of 3

Jul 29/10

The following information will be made available in the next CMM revision. In the interim all

MRO’s must adhere to the following instructions.

A. General

(1) No in situ checks are possible.

(2) Relevant sections of CMM 26-21-40 to be reviewed. 

B, Procedure (Refer to IPL Figure 1, 2 & 3)

(1) Remove the Protective Cap from the Container Neck. Install the Container in a suitable Fixture

and thoroughly clean the threads with a wire brush.

(2) Turn the Container on a horizontal axis and apply a gas flame to the threads until hot enough to

melt the solder.

(3) Brush soldering flux Material Ref. item 3 on the threads and tin with solder Material Ref. Item 4,

taking care not to overheat the Container or use an excessive amount of Solder.

(7) Install the Operating Head in a suitable Fixture e.g. T869 to allow it to be rotated on an axis with

the Operating Head 5/10 degrees below the horizontal. 

Whilst rotating the Head apply a gas flame to the threads and tin them using solder Material ref.

Item 4 and flux Material ref. item 10, taking care not to overheat the Head or use an excessive

amount of Solder. With the Head tilted at 5/10 deg. below the horizontal this will allow excess

solder to run out of the Head away from the frangible area. 

(10) Clamp Cylinder upright – thread uppermost – apply gas flame to the threads on both the Container

Neck and the Operating Head. When the Solder becomes fluid, screw the Operating Head onto

the Container Neck as far as possible using the spanner T870, ensuring the threads of the

Container bottom inside the Operating Head. Remove the Spanner T870 from the Operating

Head.

(11) Transfer the Assembly to a suitable fixture orientated Head Down and apply a small quantity of

Soldering Flux, Material Ref. item 3 around the Container/Head Joint.

CAUTION: MAKE SURE THAT NO OVERHEATING OCCURS AND THAT ONLY ENOUGH SOLDER TO

FORM AN EVEN FILLET IS USED.

(12) Apply a gas flame to the Operating Head, rotate the assembly and run Solder Material Ref. Item 4

into the Container/Head joint to form an even fillet with good adhesion between the Operating

Head and Container Neck.