The Whelen 01-0771554-01 is a 28V LED aft (tail) position light designed for aircraft exterior navigation lighting. It is part of Whelen’s 71554 series, which replaces older incandescent tail position lights (such as A555A and 71011 models) with modern LED technology for improved reliability and lower power consumption.

This horizontal-mount (H) version is used on the rear of aircraft to provide steady white navigation lighting, helping other aircraft identify position and orientation during night or low-visibility operations.

Its primary features include:
28V DC LED tail position light for aircraft navigation systems
Horizontal mount configuration (H variant)
Direct replacement for legacy Whelen incandescent tail lights
Low power draw (~0.13 A at 28V) with high efficiency 
FAA TSO-C30c Type III and STC approved aviation component 
Compact sealed design with hard-coated polycarbonate lens
Designed for vibration, weather, and long-service durability
Compatible with general aviation aircraft (Cessna, etc.)

The Whelen 71554 series is widely used in general aviation because it offers a drop-in footprint replacement for older tail lights while significantly improving visibility, reliability, and maintenance life.