TASK 70-20-00-100-001
1 . General.
Cleaning of engine parts is necessary to permit adequate detailed inspection and subsequent repair of material defects. The cleaner the parts, the more reliable will be the inspection. Completeness of weld repairing is directly dependent upon the degree of cleanliness attained before inspection; however, cleaning that is adequate for inspection may not be adequate to permit satisfactory weld repairing. Chemical solutions must be limited to use on parts that will not be subject to surface corrosion, intergranular attack, or loss of dimension. Abrasive blasting, either wet or dry, must be used in such a way as to avoid loss of dimension or surface finish, masking or hiding of cracks and flaws in metal parts. Generally, the following points should be considered in the choice of an appropriate cleaning method.
A.Type of contaminants to be removed.
B.Type of material(s) composing the part.
C.Surface finish and surface coating requirements.
D.Degree of cleanliness required.
E.Type and availability of cleaning materials and equipment.
F.Complexity of the part (geometric complications).
NOTE:
The processes described in various cleaning methods are based upon compounds supplied by a particular vendor. Materials available from other vendors may be equally satisfactory. The procedure for obtaining approval from the GE Aircraft Engines for the use of other products or parameters will be supplied upon request.
2 . Water Supply and Waste Disposal.
Subtask 70-20-00-100-011
A.Ordinary tap water is satisfactory for use in formulating most cleaning solutions described in this section. When natural or artificial inclusions of chemicals will affect the process adversely, such as chlorides or fluorides which attack titanium, the fact will be noted in the specific cleaning method. Disposal of chemical wastes must be done in accordance with local, state, and national regulations. Disposal issues should be investigated before a particular process is installed, so that facilities necessary for neutralization, filtration, or other treatment can be provided.
3 . Safety.
Subtask 70-20-00-100-012
A.Hot solutions of strong acids and caustic ingredients are serious personnel hazards; therefore, good housekeeping, safety precautions, adequate safety equipment (e.g. eye wash, safety shower, etc.), ventilation, personal protective equipment, and emergency procedures to be followed in the event of accident are of paramount importance to minimize hazards and to promote safe and efficient operation.
4 . Corrosion Prevention.
Subtask 70-20-00-100-013
A.The cleaning of parts leaves them susceptible to corrosion. After cleaning, parts must be protected during the inspection, repair, and reassembly process. For specific instructions, refer to TASK 70-60-00-620-001, Preservation of Engine Parts.
5 . Engine Materials.
Subtask 70-20-00-100-014
A.Plastic parts must be handled separately. Plastic parts are not to be submerged in cleaners or solvents unless mandated. Generally, plastic parts should be cleaned in accordance with TASK 70-21-03-160-001, Cleaning Method No. 3 - Steam Cleaning.
B.Metallic parts are to be cleaned in accordance with the cleaning methods recommended in the Engine/Shop Manual. Generally, metallic parts that have no specific cleaning method recommended may be cleaned in accordance with TASK 70-21-03-160-001, Cleaning Method No. 3 - Steam Cleaning.
6 . Acid and Alkaline Solutions.
Subtask 70-20-00-100-015
A.Cleaning methods that utilize acid and alkaline solutions must not be used where the possibility of entrapment exists since the acid and alkaline solution might not be completely removed by subsequent neutralizing/rinsing processes. The use of ultrasonic cleaning and rinsing methods greatly enhances the speed and effectiveness of cleaning many difficult parts.
7 . Use of Ultrasonic Cleaning and Rinsing Methods.
Subtask 70-20-00-100-016
A.For specific instructions, refer to TASK 70-21-15-130-001, Cleaning Method No. 15 - Ultrasonic Cleaning.
8 . Control of Rinse Water.
Subtask 70-20-00-100-017
NOTE:
The water used in rinsing shall be free of any contaminate that will leave a residue detrimental to following operations/processes on the dried component.
A.Use of overflowing rinse tanks.
(1)Incoming water should be 500 Microsiemens/cm maximum.
(2)Water continuously overflows the tank, removing rinse contaminates.
B.Use of a conductivity meter.
(1)Incoming water should be 500 Microsiemens/cm maximum.
(2)Set the control on the tank at 1,000 Microsiemens/cm to automatically turn on additional rinse water for dilution.
(3)Set the maximum limit at 2,000 Microsiemens/cm. Set the alarm to sound so that the operator can dump or drain down the rinse tank. Additional water can then be added to let the rinse bath decrease to less than 1,000 Microsiemens/cm.
C.Use a fresh water spray rinse.
(1)Incoming water should be 500 Microsiemens/cm maximum.
(2)Water is sprayed over the part with a hand pressure sprayer (<2,000 psi) until all wash residue is removed.