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
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.
18.104.22.168 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.
If instrument is operated using AC power, use a grounded power cord.
Turn power OFF before connecting or disconnecting probe cable or power cable.
1.4.7 Fluorescent Penetrant (PT) Method.
Fluorescent penetrant inspections shall be performed in accordance with the general applications and
techniques in TM 55-1500-335-23 (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 washed off 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 manufacturer.
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, MIL-1-25135, Type 1, 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