Change 2 1-21
Mechanical vibration energy generated by resonance test equipment can be measured, analyzed
by the tester, then displayed on a screen. There are several ways this energy can be applied to
material and then be analyzed. Because bonded metallic and composite material properties differ
substantially, no one test method will detect flaws in all types of material. For this reason, current
bond testing equipment incorporates at least one or more of the aforementioned features.
126.96.36.199 Safety Precautions During Bond Testing. Follow safety precautions and instructions
contained in this manual and the Nondestructive Inspection Methods manual listed in Table 1-1.
Electrical equipment shall not be operated in areas where combustible gases or
vapors may be present, unless the equipment is explosion proof.
a. If instrument is operated using AC power, use a grounded power cord.
b. Turn power OFF before connecting or disconnecting probe cable or power cable.
Fluorescent Penetrant (PT) Method.
Fluorescent penetrant inspections shall be performed in accordance with the general
applications and techniques in TM 1-1500-335-23 (Nondestructive Inspection
Methods manual) and the specific requirements of this technical manual.
The basic purpose of fluorescent penetrant inspection is to increase the visible contrast between
a discontinuity and its background. This method is performed by applying a fluorescent penetrant
solution to the inspection area which enters the surface opening of the discontinuity. The area is then
wiped or rinsed and a developer is added to draw the fluorescent material from the discontinuity. A
flaw or crack in the part will then become visible under the influence of ultraviolet light (black light).
This method is effective for detecting surface flaws in forgings, castings, extrusions, formed
sections, webs, and skins of materials. The penetrant method of inspection requires that the surface
of the inspection area be thoroughly cleaned. Paint on the part must be removed before inspection.
Penetrant-Emulsifier/Remover Combinations (lipophilic/hydrophilic) from one
manufacturer may not be mixed or used in conjunction with materials from a different
Four penetrant procedures are given in Tables 1-3, 1-4, 1-5, and 1-6. All four inspections shall be
conducted using fluorescent penetrant, AMS 2644, Type I, Method A, B, C, or D, Sensitivity Level
3 or 4. Refer to the Nondestructive Inspection Methods manual listed in Table 1-1 for more detailed
instructions. Table 1-5 describes the procedure for using Type I, Method C, Level 3 or 4 on a removed
part or parts attached either to a component or to the helicopter. This procedure supports the
accomplishment of fluorescent penetrant inspection at the AVUM and AVIM levels regardless of
geographic location. Therefore, the procedure in Table 1-5 will be the one most frequently referred
to in this manual. Table 1-7 lists the equipment and Table 1-8 lists the fluorescent penetrant materials
to be used.