Communications: Honeywell RTA 44D VHF Transceivers

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FAA Aviation Safety SPECIAL AIRWORTHINESS INFORMATION BULLETIN SUBJ: Communications: Honeywell RTA 44D VHF Transceivers SAIB: NM-14-21 Date: June 3, 2014 This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin alerts operators, repair stations, mechanics holding Inspection Authorizations (IA), Flight Standards District Offices (FSDO) Principal Maintenance Inspectors (PMI) and/or Principal Avionics Inspectors (PAI) of service difficulties associated with off-frequency transmissions from airplanes installed with Honeywell RTA-44D VHF Data Radios on Airbus A318, A319, A320 and A321 series airplanes.

At this time, the airworthiness concern is not an unsafe condition that would warrant airworthiness directive (AD) action under Title 14 of the Code of Federal Aviation Regulations (14 CFR) part 39.

Background

There have been reports of spurious voice transmissions from Airbus single aisle airplanes equipped with Honeywell RTA-44D very high frequency (VHF) transceivers part numbers (P/N) 064-50000-0202 and P/N 064-50000-0505 at some airport locations in the US and Europe. The off-frequency transmissions do not always occur but can interfere with air traffic control operations. The operating flight crew of the affected airplane would not be aware of interference. Honeywell identified that the RTA-44D spurious interference is a result of an anomaly in the radio and a combination of factors including length of coaxial cable and transient factors such as unusually high voltage on the 28VDC bus and unusually low cooling temperature. Reported incidents of spurious transmissions have occurred only with the RTA-44D, in the VHF 1 position, when transmitting on frequencies below 121 MHZ. These transmissions are only heard when another radio is using a frequency that is 8.3 MHz above the tuned VHF 1 frequency. Susceptible frequency pairings are known to exist around JFK, New York and Brussels, Belgium; they could also exist in other locations that have not filed reports of interference or that have recently changed their frequencies.

Honeywell issued Service Bulletin 064-5000-23-4, dated April 25, 2013. The service information provides procedures for installing RTA-44AD transceivers with MOD 22 standard incorporated.

Recommendations

The FAA recommends that US operators of affected Airbus A318, A319, A320 and A321 series airplanes implement Honeywell Service Bulletin (SB) 064-5000-23-4 and ensure RTA-44AD transceivers with MOD 22 standard incorporated is installed when operating in airspace prone to off- frequency transmission interference. In the interim, flight crews of airplanes with affected radios may prevent the situation from occurring by using VHF 2 for tower communications at JFK, BRU and other locations if interference has been observed.

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Sanjay Ralhan, Aerospace Engineer, FAA, Transport Airplane Directorate, International Branch, ANM-116, 1601 Lind Ave. SW, Renton, Washington, 98057-3356; phone: (425) 227-1951; fax: (425) 227-1149; email: [email protected].

For Related Service Information Contact

Honeywell International, 15001 NE 36th Street, Redmond, WA, 98052-5317; phone: 800-601-3099 or International Direct phone: 602-365-3099.