Finding and fixing aircraft fuel tank leaks has always been an arduous and time-consuming process, many times best left to a specialists. Generally, the aircraft is pulled from service and parked in a hangar or designated safe area.

The general area of the leak is marked; the tank defueled, opened, vented and allowed to dry. Next, the AMT dresses in anti-static clothing, ensures that the tank environment meets safety standards, and enters the tank. The area in question is located, sealant removed, and fasteners replaced if necessary. The worked area is cleaned and prepped for the reseal. The sealant is allowed to dry and openings are closed. The tank is pressurized with shop air and the suspected area is sprayed with a soap solution. AMTs watch for telltale bubbles. If they do appear, the process is repeated, and oversized fasteners are installed and/or another round of sealant is applied. If no bubbles appear, the tank is refueled and put on watch for leaks. If no leaks appear, the aircraft can be returned to service.

Fixing leaks is a big part of an AMT’s professional life. It is also big business.


Recently, another group of leak-finding experts has given aircraft owners and operators and AMTs another product to help pinpoint aircraft fluid leaks. Spectronics Corporation has been a good friend to a variety of maintenance departments for a long time. It invented fluorescent leak detection and has provided us with ultraviolet dyes and inspection lamps for over a half a century. The 200-employee company headquartered in Westbury, NY manufactures and distributes more than “1,000 different UV, UV/Blue and LED products that are used to find flaws and leaks in a multitude of mechanical systems.”

UV Fluorescent dye for Aircraft Fuel Systems. Checks an entire system in just minutes! Ideal for use as part of a diagnostic/preventive maintenance program for commercial and military aircraft fuel and fluid systems! Fluoresces Green.

It produces the Aero-Brite universal fluorescent leak detection dye that can be used to locate leaks in all petroleum- and synthetic-based aviation fluid systems. Aero-Brite is “safe to use in aircraft fuel, hydraulic and lubricating systems” and “safe to use in turbine and reciprocating engines.” Using the Aero-Brite for leak detection is about as easy as it gets. You add a prescribed amount of fluorescent dye to the leaking fluid system and let it circulate.

It can be used under all normal operating conditions and temperatures. When the mixture escapes at the leak site, it glows a bright fluorescent yellow-green color when illuminated with a Spectroline high-intensity UV inspection lamp. The Aero-Brite comes in three different quantities, and the OPX- 365 UV LED flashlight with a 20-foot inspection range can be used to check for leaks in those hard-to-get-to places.

According to Daniel Cooper (sales account manager at Spectronics Aviation Division), the MAXIMA aviation leak detection kit would be a better solution for specialty shops and crews needing a more robust system. Cooper suggests that “using the fluorescent leak detection products will help decrease the number of aircraft grounded for repair work.” As a tip to AMTs using Aero-Brite, the company recommends that “wherever possible, leak sites should be scanned with the UV lamp under low ambient light conditions in order to enhance the fluorescent response of the dye.”