What are less-hazardous ways to identify pinhole leaks within the aircraft fuel cell system?


Posted: November 16, 2022

Deadline: December 9, 2022

The Homeland Defense and Security Information Analysis Center (HDIAC) is looking for less-hazardous alternatives to identify pinhole leaks within the aircraft fuel cell system.

Currently, a Phenolphthalein indicator test that reacts with ammonia is used to identify holes in the fuel bladder. “Zyglo,” a liquid fluorescent penetrant, is used to identify cracks in the fuel cell structure. Both ammonia and “Zyglo” have hazardous effects to the user over time, even with the use of personal protective equipment, which creates a health concern.

Additional information:

Fuel Bladder Leaks – When a leak is suspected in the bladder of a fuel cell, the process is to remove the bladder from the aircraft. Phenolphthalein is placed inside the bladder. The covers and caps are installed to seal the bladder, ensuring fumigation within. Air is then pumped in to pressurize the bladder, and a rag is soaked in ammonia and draped over the bladder. Because of the chemical reaction between the base (ammonia) and the indicator (Phenolphthalein), a purple dot appears on the rag to indicate the location of a pinhole leak.

Fuel Cell Structure Leaks – The cells within the aircraft are not without leaks. Rivets, bolts, or just the walls (baffles) may have cracks that have to get reinforced or filled in with sealant. “Zygo” is used to find those hard-to-see leaks.

If you know of any relevant information or key contacts, please fill out the attached Active Inquiry form and e-mail to Deanna Milonas (deanna.c.milonas.ctr@mail.mil), the lead IAC analyst, or on the DoDTechipedia forum by clicking the “Join the Discussion” button below.

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