TASK 70-33-02-220-005
1 . General.
A.This inspection is used to check the integrity of the bond between honeycomb cells, cell walls, and the base following brazing. This examination process reveals brazing discontinuities in the honeycomb structures through visual observation for fluid entering the cells and by fluid retention. Unbonded cells tend to fill with liquid rapidly, and will also empty rapidly, both due to a lack of capillary forces. Bonded cells do not fill easily with liquid, and will retain fluid, both due to strong capillary forces. Two different test methods utilize these facts in this inspection technique.
NOTE:
Visual inspection systems approved by GE Aircraft Engines - Repair Engineering will be considered as alternate equivalent inspection procedures for inspection of open face honeycomb structures. Equipment identified to perform such an inspection can be found in C05-113    and C05-114  .
2 . Equipment.
Subtask 70-33-02-220-051
A.A tank large enough to contain the inspection fluid and allow inspection part to be immersed.
3 . Materials.
Subtask 70-33-02-220-052
 
Consumable Product
No.
 
Kodak Photo-Flo Solution
S1169
 
Orvus WA Solution
S1200
 
Isopropyl Alcohol
C05-127
4 . Procedure 1.
Subtask 70-33-02-220-053
A.Ensure that part to be inspected is clean and free from all dirt, grease, and oil.
B.Immerse the inspection part in one of the inspection fluids shown in Subtask 70-33-02-220-052 , Materials. Use the instructions that follow:
NOTE:
If the parts are small and flat, they can be immersed in the inspection fluid at one time. If the parts are cylindrical, they will need to be marked into convenient sectors for proper inspection.
(1)Insert the part, cell openings upward, into the liquid at an angle in order to allow air to escape from the cells.
(2)Ensure all honeycomb cells are filled with inspection fluid before removing part from tank.
C.Carefully withdraw the inspection part from the inspection fluid bath being careful not to jar the part or spill fluid from the honeycomb cells. Prevent any contact with area to be inspected.
D.Visually examine the honeycomb to find any cells that fail to hold the inspection fluid.
(1)After the part has been removed from the inspection fluid, slowly rotate the part around the axes of the honeycomb surface to be inspected. Angles of rotation shall be both positive 90 degrees and negative 90 degrees around the stated axes when measured from the horizontal.
NOTE:
If the part has a shape difficult to inspect with one immersion, it may be necessary to process it a sector at a time.
(2)Identify those cells that are partially or completely empty.
NOTE:
Completely empty cells indicate lack of bond between honeycomb and base. Partially empty cells, a void between cell walls.
E.Accept or reject parts in accordance with limits specified for particular parts in the process document.
F.Remove the solvent from the honeycomb cells by inverting the parts over the solvent container and shaking the part vigorously.
5 . Procedure 2.
Subtask 70-33-02-220-055
NOTE:
Procedure 2 is not recommended for honeycomb cell sizes larger than 1/16 inch (1.6 mm) diameter.
A.Ensure that part to be inspected is clean and free from all dirt, grease, and oil.
B.Immerse the inspection part in the inspection fluid as follows:
NOTE:
If the parts are small and flat, they can be immersed in the inspection fluid at one time. If the parts are circular, they will need to be marked into convenient sectors for proper inspection.
(1)Insert the part, cell openings upward, into one of the liquid inspection fluids shown in Subtask 70-33-02-220-052, Materials.
(2)For 30-60 seconds, carefully observe the rate at which the honeycomb cells fill with the inspection liquid. Defective cells will appear dark colored, while completely bonded cells will form an air bubble and prevent fluid from quickly entering the cells and appear bright as they reflect light back. For an example, see Figure 1.
C.Carefully withdraw the inspection part from the inspection fluid bath being careful not to jar the part or spill fluid from the honeycomb cells. Prevent any contact with area to be inspected.
D.Visually examine the honeycomb while keeping the honeycomb in a horizontal position. Identify as defective those cells that appear dark.
NOTE:
The defective area may be marked while the part is still immersed to ease inspection.
E.Accept or reject parts in accordance with limits specified for particular parts in the process document.
F.Remove the solvent from the honeycomb cells by inverting the parts over the solvent container and shaking the part vigorously.
* * * FOR ALL
Figure 1   Example of Good Cells Reflecting Light Back (Light Areas) and Defective Cells (Dark Areas) (Procedure 2)
6 . Quality Assurance.
Subtask 70-33-02-220-054
A.Visually examine inspection fluid to determine if it has been contaminated with foreign material. Inspection fluid must remain clear and free of floating particles for proper inspection. Replace if contaminated or discolored.