# Service Informa tion 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 S u m m a ry 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. S e rv i c e I n fo r m a t i o n L e tt e r Re v i s i o n H i s t o ry

REVISION DATE OF RELEASE Initial Release September 27, 2007

Revision 1 September 2, 2008

Export Control Classi fi cation Notice (ECCN) for this document is 6E991. © Copyright, 2008 Rockwell Collins, Inc., All rights reserved Sep 27/07 TDR-94( ) SIL 07-2 1-Sep 2/08 Page 1 of 3

# 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 identi fi cation 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)

Sep 27/07 TDR-94( ) SIL 07-2 1-Sep 2/08 Page 2

# 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

Sep 27/07 TDR-94( ) SIL 07-2 1-Sep 2/08 Page 3