Rockwell Collins TPR 901 Mode S Transponder - Incorrect —Downlink Aircraft Identification— and Incorrect Operation with Airport Ground Tracking Systems
- Published
AI-generated summary of the official EASA document. Verify against the PDF before acting.
What to do
Operators of affected aircraft should modify their Rockwell Collins TPR 901 transponders according to Rockwell Collins Service Bulletin 503 or Boeing Service Bulletin 747-34-3003 for Boeing 747-400 aircraft. They should avoid installing the earlier SB 15 modification and consult Rockwell Collins Service Information Letter 11-1 for updated approved model lists. For further details or service publications, stakeholders should contact EASA or Rockwell Collins directly.
Summary
EASA Safety Information Bulletin SIB No. 2011-20R1 addresses issues with the Rockwell Collins TPR 901 Mode S transponder, Part Number 822-1338-003, installed on various aircraft including Boeing 747-400 series modified under FAA STC ST01202WI-D and its European validation. The bulletin highlights problems with incorrect downlink aircraft identification and improper operation with airport ground tracking systems caused by certain transponder modifications. It provides information on service bulletins and recommended corrective actions to resolve these anomalies.
What changed
This bulletin updates previous information by describing the transient problem introduced by the original transponder and the subsequent issues caused by Rockwell Collins Service Bulletin 15 modifications. It details the issuance of SB 15 Revision 1 to halt installation of the initial fix, the release of SB 16 to revert changes, and the later SB 503 which corrects the identification problem with a new part number 822-1338-005. Boeing also published SB 747-34-3003 to update the transponder part number for 747-400 aircraft.
Why it matters
These transponder anomalies increase workload for air traffic controllers and flight crews due to incorrect aircraft identification and tracking issues. Although not currently considered an unsafe condition warranting an Airworthiness Directive, the problems affect operational efficiency and situational awareness. Operators and maintenance organizations need to be aware of the correct modification status to ensure proper transponder function and compliance with recommended service instructions.
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