AD 88-09-03 ACTIVE

88-09-03 LOCKHEED-GEORGIA: Amendment 39-5903. Applies to Model 382 series airplanes, certificated in any category.

Compliance required as indicated, unless previously accomplished.

To prevent failure of the control column and loss of control of the airplane, accomplish the following:

A. Within the next 250 hours time-in-service after the effective date of this AD, perform an eddy current (non-destructive) inspection of the left and right control column bases on the forward side of each control column at approximately floor level, as follows:

NOTE: The control column base is shown in the Lockheed Hercules Component Overhaul Manual, SMP 850, Item 27-26, figure 1, page 4, as Figure Item No. 235 (see Figure 1, below). The inspection area is around the 1.25-inch diameter hole located on the forward side of the base approximately at the lower end of the control column tube support (Figure Item No. 185).

The control column bases are fabricated from either magnesium or aluminum. Earlier airplanes were delivered with AZ916-T6 magnesium alloy sand castings per MIL-M-4204. The magnesium castings are finished with an anodic treatment, a wash primer per MIL-C-8514, and two coats of epoxy primer per LAC 37-722, Type I, followed by an epoxy enamel per LAC 37-722 of appropriate color. The aluminum bases are A356-T6 aluminum castings per MIL-A- 21180, Class 10, with an initial sulfuric acid anodize, and finished with two coats of zinc chromate primer, followed by two coats of Camouflage lacquer per TT-L-190.

Fatigue cracking may initiate at the sharp edge formed by thickness transition approximately mid-way up from the bottom of the 1.25-inch diameter hole on the forward side of the base. Cracks will propagate aft around the perimeter of the base along the thickness transition.

1. Prior to performing the eddy current inspection, assemble the following equipment:

a. Crack Detector, Magnaflux P/N ED-520, or equivalent.

b.Probe, surface, shielded, 1/8-inch diameter, 8 inches long, VM products P/N VM200-8, or equivalent.

c. Probe, surface, shielded, right angle, 1/8-inch diameter, 1/2-inch drop, 8 inches long, VM Products P/N VH202BA-1/2-8, or equivalent.

d. Cable, 6 foot, Microdot/BAC, Mastercraft Enterprises P/N NMT 7-41-BM, or equivalent.

e. Standard, aluminum, as furnished with the Magnaflux instrument, or Lockheed-Georgia Company P/N PDL 457A.

2. Prior to performing the eddy current inspection, prepare the airplane in the following manner:

WARNING:

Ensure that power is isolated from all systems in the inspection area prior to approaching the inspection area. Failure to comply may result in serious injury to personnel.

a. Isolate power from all systems in the inspection area in accordance with applicable maintenance manuals.

b. Remove screws retaining Dust Seal Boot (Figure Item No. 20, Item 27-26 of SMP 850) to the cockpit floor. Loosen clamp retaining the Dust Seal Boot to the Support Tube, and push the Dust Seal Boot up approximately 6 - 8 inches and secure to Support Tube temporarily. Repeat for opposite control column installation.

3. Gain access for the inspection inside of the airplane in the cockpit, using normal ingress provisions.

4. Prepare the area to be inspected as follows:

a. Remove oil grease, residual, sealant, and other materials by wiping the control column base around the 1.25-inch diameter hole on the forward side of the base with Federal Specification 0-T-620, Type I, Trichloroethane, or commercial equivalent, and dry with clean cotton cloth.

WARNING:

Federal Specification 0-T-620, Type I, Trichloroethane is toxic to skin, eyes, and respiratory tract. Skin and eye protection is required. Avoid repeated or prolonged contact. Good general ventilation is normally adequate. Failure to comply could result in injury to personnel.

b. Visually inspect area to be inspected, looking for rough surface conditions which could adversely affect the eddy current inspection. If surface appears rough, smooth surface using 320 grit sandpaper until a reliable eddy current inspection can be achieved.

5. Set up and calibrate the eddy current instrument as specified in Lockheed Service Manual SMP-515-A or SMP-515-C, Work Card SP-76, Appendix A, for surface scanning on aluminum. The eddy current instrument must be recalibrated when probes are changed. Calibrate on aluminum for inspection of the magnesium casting.

6. Perform the eddy current inspection in the following manner:

a. With the control column in the full aft position, surface scan around the entire circumference of the 1.25-inch diameter hole at the front of the control column base casting, using both eddy current probes. Scan in both clockwise and counterclockwise directions.

b. Repeat this inspection on the opposite control column base.

7. If any suspected defects in thecontrol column base casting are found during the eddy current inspection, indicated by a sharp meter deflection noted during calibration, mark the suspected defect.

a. To confirm suspected defects, proceed to paragraph B., below.

b. If no defects are suspected, proceed to paragraph C., below (System Securing).

B. To confirm suspected defects, perform a fluorescent penetrant inspection as follows:

1. Prior to performing the fluorescent penetrant inspection, assemble the following equipment:

NOTE: All chemicals shall use the "family concept" - they shall all be from the same manufacturer for Type I, Group VI, Method C, per MIL-I-25135.

a. Penetrant, fluorescent, Magnaflux P/N ZL-22A, or equivalent.

b. Remover, penetrant, Magnaflux P/N SKC/NF/ZC-7B, or equivalent.

c. Developer, penetrant, Magnaflux P/N ZP-9b, or equivalent.

d. Black light, portable, Magnaflux P/N ZB-26, or equivalent.

2. Prior to performing the fluorescent penetrant inspection, prepare the airplane by removing the control column assembly from the airplane in accordance with the applicable maintenance document.

3. Gain access for the inspection inside of the airplane in the cockpit, using normal ingress provisions.

4. Prepare the area to be inspected, in accordance with Lockheed Service Manual SMP 515-A or SMP 515-C, Work Card SP-76, Appendix A, for stripping finish around the 1.25-inch diameter hole in the suspect area.

WARNING:

Paint strippers are dangerous chemicals to humans and aircraft. Every effort must be made to prevent inadvertent contact with any portion of the person or aircraft. Should accidental contact be made, immediately flood the contacted area with water, and, in the case of personal contact, seek immediate medical attention.

5. Perform the fluorescent penetrant inspection in the following manner:

NOTE: If the temperature of the part or inspection materials to be used is below 60 degrees F (16 degrees C), preheat and maintain the temperature at or above 60 degrees F (16 degrees C) during application of penetrant materials. The surface may be heated with a hot air heater.

a. Pre-clean the area to be inspected with the solvent cleaner (Remover, SKC/NF/ZC-7B) and wipe with a clean, dry, lint free cotton cloth.

b. Apply warm air to the inspection area to remove all moisture.

c. Apply penetrant to the control column base with penetrant sprayed onto a cotton swab and brushed onto the part. Do not spray the part from the penetrant spray can. Allow a minimum dwell time of 10 minutes before proceeding to the next step.

d. Wipe inspection area with a clean, dry, lint free cotton cloth. Wipe remaining penetrant from part with a clean, lint free cotton cloth dampened with the penetrant remover. Check the area to be inspected with the black light to ensure that excess penetrant has been removed prior to applying the developer.

e. Spray alight film of developer over the area to be inspected. Allow a minimum dwell time of 5 minutes.

f. Using the black light, inspect the suspect area for defects.

6. If defects are confirmed, prior to further flight replace the control column base with a serviceable unit free of cracks. After replacement of the control column base, or if no defects are found, proceed to paragraph C., below (System Securing).

C. System Securing: Restore finishes and sealants, reinstall removed components, remove equipment and supplies from the inspection area; rig control system in accordance with applicable maintenance manual; and perform operation checkouts as required in accordance with applicable maintenance instructions.

D. An alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety and which has the concurrence of an FAA Principal Maintenance Inspector, may be used when approved by the Manager, Atlanta Aircraft Certification Office, FAA, Central Region.

E. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD.

All persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to Lockheed-Georgia Company, 86 South Cobb Drive, Marietta, Georgia 30063. These documents may be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, or FAA, Central Region, Atlanta Aircraft Certification Office, 1669 Phoenix Parkway, Suite 210, Atlanta, Georgia.

This amendment 39-5903 becomes effective June 7, 1988.