Liquid Penetrant In The Aerospace Industry

The Qualified Products List (QPL)

            The aerospace industry relies upon Type 1 fluorescent penetrant systems for the detection of defects in aircraft and engine components during maintenance and overhaul operations. Liquid penetrant specifications, such as ASTM E-1417 and AMS-2647, are considered industry standards for in-process, final, and maintenance (in-service) penetrant examinations for the final acceptance of aerospace products. These widely used specifications state that only materials listed and approved to QPL-AMS-2644 shall be utilized for penetrant examination. This is an important rule in the aerospace industry because only these materials have been quality tested by an approved laboratory.

The United States Air Force Materials Command

            Type 1 fluorescent penetrant systems are approved for use by The United States Air Force Materials Command (USAFMC) at the Air Force Materials Research Laboratory (AFRL) at Wright Paterson Air Force Base in Dayton, Ohio. Only materials stating “certified to AMS 2644” are approved for use, not materials or manufacturers that state “meets the requirements of AMS2644”. Approved materials are recorded on the Qualified Products List (QPL) and certified by the manufacturer in accordance with AMS-2644. Materials listed on the QPL meet the rigorous requirements of the following:

  • NADCAP quality programs

  • FAA and EASA repair stations

  • AS9100 and ISO 9001:2015 quality systems

  • OEM aerospace manufacturers: Airbus, Boeing, General Electric, Gulfstream, Honeywell, Hamilton Sundstrand, Pratt & Whitney, Parker Hannifin, Rolls-Royce.

Common Liquid Penetrant Aerospace Systems



Sensitivity Level 1 – Low: FP-921 , FBP-911

Sensitivity Level 2 – Medium: FP-922, FBP-912, FP-93A(M)

Sensitivity Level 3 – High: FP-923, FBP-913, FP-95A(M)

Sensitivity Level 4 – Ultrahigh: FBP-914, FP-97A(M)

Developer Form a – Dry powder: D-72A

Developer Form b – Water-soluble: D-76B

Developer Form c – Water-suspendable: D-78B

Developer Form d – Nonaqueous: D-70


Lipophilic: E-57

Hydrophilic: E-58D


Solvents: E-59A, R-503, R-504

Alkaline: 300LF