Q4681 - GE Lamp Light Bulb

Q4681 – GE Lighting Quartzline® Aircraft Lamp

Part Number: Q4681

Manufacturer: GE Lighting (Current / Tungsram)

Standard Compliance: ANSI Q4681

Common Synonyms: PAR36 Landing Light, Quartz-Halogen Taxi Light, 28V 150W Bulb

Overview Section

The Q4681 is a high-intensity Quartz-Halogen sealed beam lamp designed for primary aircraft exterior lighting. Featuring the standard PAR36 (4.5-inch diameter) form factor, this lamp is a high-performance upgrade over traditional incandescent bulbs. It is primarily utilized as a Taxi Light or Recognition Light on 28V electrical systems common to turbine and high-performance piston aircraft.

Unlike standard lamps, the Q4681 uses Quartzline® technology—a halogen cycle process that prevents the internal blackening of the glass envelope. This ensures that the lamp maintains nearly 100% of its initial light output (luminous flux) throughout its entire service life, providing pilots with consistent, reliable visibility during ground operations and low-altitude flight.

Enhanced Technical Data

Advanced Engineering & Structural Application

The Q4681 is engineered for Durability and Optical Consistency. In the aviation environment, taxi lights are often left on for extended periods during ground holds, leading to significant heat buildup.

Engineering Insight: The Halogen Cycle Advantage

The Q4681 utilizes a pressurized halogen gas charge. As the tungsten filament evaporates, the halogen gas chemically bonds with the tungsten atoms and redeposits them back onto the filament rather than on the glass.1 This "self-cleaning" cycle allows the filament to run at higher temperatures—producing a whiter, brighter light (approx. 3000K) compared to the yellowish tint of standard incandescent lamps.

Mechanical Robustness

The PAR36 "Sealed Beam" construction protects the reflector and filament from the elements.2 The borosilicate glass lens is designed to resist thermal shock, which is critical when an aircraft transitions from a warm hangar to a sub-zero flight line or encounters rain during taxi.

Aircraft Compatibility

The Q4681 is a standard-fit lamp for a wide variety of 28V aircraft:

• Cessna Citation / Beechcraft King Air: Frequently used as a taxi light in the nose gear or wing root.

• Piper Cheyenne & Navajo: Standard recognition or taxi light.

• Corporate Jets: Compatible with many Gulfstream and Learjet auxiliary lighting housings.

• General Aviation: An ideal 28V high-performance replacement for older 150W incandescent PAR36 lamps.

The GE Q4681 is the professional pilot's choice for superior ground visibility. When navigating complex taxiways at night or in low-visibility conditions, the 150-watt output of this Quartz-Halogen lamp provides a wide, penetrating beam that highlights taxiway markings and potential hazards. With a rated life of 1,000 hours, the Q4681 lasts significantly longer than standard incandescent lamps, reducing maintenance downtime and bulb replacement costs. Trust the heritage of GE Lighting to provide the optical clarity and rugged performance required for safe all-weather flight operations.

Installation & Maintenance Addendum

1. Terminal Security: When installing the Q4681, ensure the screw terminals are tightened firmly but not over-torqued. Use specialized high-temperature ring terminals to prevent wire fatigue near the lamp base.

2. Gasket Replacement: Always inspect the rubber mounting gasket (lens seal) when replacing the lamp. A cracked gasket can allow moisture into the light bucket, leading to terminal corrosion and premature lamp failure.

3. Lens Orientation: Ensure the "TOP" marking on the lens is oriented correctly according to the aircraft maintenance manual to achieve the intended horizontal beam spread for taxiing.

ALT P/N 4581