Service Information Letter

523-0810069-101000

TDR-94 ATC/MODE S TRANSPONDER (622-9352-008/108/308/408)

TDR-94D ATC/MODE S TRANSPONDER (622-9210-008/108/308/408)

Service Information Letter 07-2

REVISION NO. 1

MODE-S ONLY ALL-CALL REPLY INHIBITION

TRANSMITTAL INFORMATION SUMMARY

Summary

This is revision 1 of SIL 07-2 for the TDR-94/94D ATC/Mode S Transponder.

This revision adds information about the release of TDR-94/94D Service Bulletin 505 and the

solution for installations that do not have the upgrade installed.

Black bars in the margins indicate the changes.

Replace the original issue with this revision.

Service Information Letter Revision History

REVISION DATE OF RELEASE

Initial Release September 27, 2007

Revision 1 September 2, 2008

Export Control Classification Notice (ECCN) for this document is 6E991.

© Copyright, 2008 Rockwell Collins, Inc., All rights reserved

Sep 27/07 TDR-94( ) SIL 07-2

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Service Information Letter

Description:

The TDR-94/94D (-008/108/308/408) does not properly enable replies to Mode-S Only All-Call

interrogations when the aircraft transitions from a ground to an airborne state. The transponder

does properly reply to all ATCRBS and directed Mode-S interrogations, including TCAS, after the

transition. The Mode-S Only All-Call replies are inhibited due to an error in the air/ground override

function. The override function is only enabled if the Aircraft Type Code Category A strapping is

set to values of 2 through 6. This function should transition the transponder to the airborne state

when True Airspeed or Groundspeed exceeds 100 knots or Radio Altitude exceeds 50 feet.

The function is intended to overcome a faulty strut switch and prevent an airborne aircraft from

incorrectly reporting it is on-ground. However, when the override function is enabled and activated

prior to aircraft rotation, it will erroneously inhibit the replies to Mode-S Only All-Call interrogations.

The Aircraft Type Category identification strapping is part of future Automatic Dependent

Surveillance-Broadcast (ADS-B) functionality. The strapping is used only for ADS-B and does not

affect other transponder functions.

Solution:

Rockwell Collins, Inc. has released Service Bulletin 505 for the TDR-94/94D. The Service Bulletin

upgrades -008/308 units to -309 and -108/408 units to -409. The new part numbers (-309/-409)

include corrections to the air/ground override function. Service Bulletin 505 is highly recommended

to all customers with existing -008/108/308/408 status units installed in their aircraft.

In installations that have not yet been upgraded to -309/409 units, it is recommended that the

Aircraft Type Category strapping be set to a value of zero (0) or one (1) in order to prevent the

preceding situation from occurring. Aircraft weighing less than 15,500 lbs. should continue to set

the Aircraft Type Category to one (1) (Light). Aircraft weighing 15,500 lbs. or more should set the

Aircraft Type Category to zero (0) (No aircraft type information). This is particularly critical if the

aircraft has a rotation speed greater than 100 knots.

Aircraft Type Category Strapping Connections:

TYPE 2

P1-22

TYPE 1

P1-21

TYPE 0

P1-20

CODE MEANING

TYPE SET A (P1-23 = OPEN)

Open Open Open 0 No ADS-B Category type information

Open Open Gnd 1 Light (<15,500 lbs)

Open Gnd Open 2 Small (15, 000 to 75,000 lbs)

Open Gnd Gnd 3 Large (75,000 to 300,000 lbs)

Gnd Open Open 4 High Vortex - Large (aircraft such as B-757)

Gnd Open Gnd 5 Heavy (>300,000 lbs)

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Service Information Letter

TYPE 2

P1-22

TYPE 1

P1-21

TYPE 0

P1-20

CODE MEANING

Gnd Gnd Open 6 High Performance (>5g acceleration and >400 knots

Gnd Gnd Gnd 7 Rotor Craft

TYPE SET B (P1-23 = GND)

Open Open Open 0 No ADS-B Category type information

Open Open Gnd 1 Glider/Sail Plane

Open Gnd Open 2 Lighter-than-Air

Open Gnd Gnd 3 Parachutist/Skydiver

Gnd Open Open 4 Ultralight/Hang-glider/Paraglider

Gnd Open Gnd 5 Reserved

Gnd Gnd Open 6 Unmanned Aerial Vehicle

Gnd Gnd Gnd 7 Space Trans-atmospheric Vehicle

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