The FAA is giving operators 135 days to inspect some 3,800 Honeywell emergency locator transmitters (ELTs) for risks of fire, closely following a Canadian directive issued last month.

Set for publication today as a direct final rule, the FAA rule calls for a one-time visual inspection of ELTs and related transmitter units (TUs). The checks should focus on the condition of battery covers, wires and insulation; damage to TU wires; and deformation or other “discrepancies” in the battery cover gaskets, the FAA says in the directive.

The checks are based on Honeywell guidance last updated Aug. 8 and adopted by Canadian regulators a week later. They apply to Honeywell Model RESCU 406AF and 406AFN ELTs with TU part numbers 1152682-1, -2, and -3.

FAA’s directive is effective Oct. 2. Operators then have 120 days, or until Jan. 30, to complete the checks.

The agency acknowledges that a 120-day compliance window is “unusually long” for a direct final rule, explaining it chose the timeframe to minimize flight schedule disruptions. The Canadian order gives operators 150 days to perform the checks.

These ELT checks, mandated in Europe shortly after Canada issued its order, stem from the probe of a July 12 fire on an empty Ethiopian Airlines Boeing 787 at London Heathrow Airport. Investigators suspect the fire’s source was the 787’s RESCU 406AFN ELT or related wiring. The Ethiopian incident remains unique, though inspections by other 787 operators soon after the mishap turned up damaged wires on three units.

The two Honeywell ELTs have been certified as buyer- or supplier-furnished equipment (BFE/SFE) on 11 models, including most current-production Airbus and Boeing aircraft. They are available for retrofit on 18 models, including seven in the BFE/SFE category.

Honeywell has delivered about 3,000 of the 406AFNs and 2,500 406AFs.

Boeing says that some 1,100-1,200 of its aircraft have been delivered with one of the two ELTs. Fewer than 100 Airbus aircraft have been delivered with one of the units. The FAA’s directive estimates that there are 3,832 affected ELTs on U.S.-registered aircraft, but does not provide a model-specific breakdown.