AD 79-18-03

79-18-03 MCDONNELL DOUGLAS: Amendment 39-3541 as amended by Amendment 39-3603. Applies to DC-10-10, -10F, -30, -30F and -40 airplanes. Serial numbers corresponding to manufacturer's fuselage Numbers 1 through 258, certificated in all categories.

Compliance is required as indicated.

To reduce the possibility of an unannounced anti-ice system failure accomplish the following, unless modified per Paragraph (c) of this AD.

a. Within the next 300 hours' time in service from the effective date of this AD, unless previously accomplished within the last 3,000 hours' time in service, accomplish the tests specified below.

TEST PROCEDURE FOR WING/ANTENNA ANTI-ICE SYSTEM PASSIVE FAILURES

1. Remove power from all AC and DC buses.

2. Open "BATT DIRECT & LEFT EMER DC FEED" circuit breaker on overhead CB panel.

3. Disconnect P1-837 at center accessory compartment right hand (CAC-R) disconnect panel.

4. Restore power to DC buses 1 and 3. (Other buses may be energized if desired.)

5. Pressurize No. 3 pneumatic system to at least 15 psig per instructions in Maintenance Manual Chapter 36-00-00.

6. Place WING & ANT ANTI-ICE switch to TEST position and verify that WING & ANT ANTI-ICE DISAGREE light comes on and goes off.

CAUTION: WING ICE PROTECTION MUST NOT BE OPERATED IN TEST POSITION ON THE GROUND WITH ENGINES OR APU OPERATING OR WITH PNEUMATIC GROUND SUPPLY CONNECTED FOR MORE THAN 30 SECONDS. FAILURE TO OBSERVE THIS PRECAUTION CAN RESULT IN OVERHEATING WING LEADING EDGES, CAUSING DAMAGE.

NOTE: The above caution is not applicable if an external ground pneumatic source with air temperature controlled at 190 degrees F (88 degrees C) or less is used.

7. Release WING & ANT ANTI-ICE switch and verify WING & ANT DISAGREE light comes on and goes off.

8. Depressurize No. 3 pneumatic system, remove power from all AC and DC buses, and verify "BATT DIRECT & LEFT EMER DC FEED" circuit breaker is open.9. Reconnect P1-837 at CAC-R panel and restore power to aircraft as required.

10. Open "WING & ANT ANTI-ICE DISAGREE LTS" circuit breaker on upper main CB panel.

11. In lower galley or forward cargo area as applicable, gain access to antenna valve.

12. Disconnect P1-2472 from antenna valve position switches.

13. Close circuit breaker listed in Step 10.

14. Pressurize No. 3 pneumatic system to at least 15 psig per instructions in Maintenance Manual Chapter 36-00-00.

15. Place WING & ANT ANTI-ICE switch to TEST position and verify that WING & ANT ANTI-ICE DISAGREE light comes on and goes off.

CAUTION: WING ICE PROTECTION MUST NOT BE OPERATED IN TEST POSITION ON THE GROUND WITH ENGINES OR APU OPERATING OR WITH PNEUMATIC GROUND SUPPLY CONNECTED FOR MORE THAN 30 SECONDS. FAILURE TO OBSERVE THIS PRECAUTION CAN RESULT IN OVERHEATING WING LEADING EDGES, CAUSING DAMAGE.

NOTE: The above caution is not applicable if an external ground pneumatic source with air temperature controlled at 190 degrees F (88 degrees C) or less is used.

16. Release WING & ANT ANTI-ICE switch and verify WING & ANT DISAGREE light comes on and goes off.

17. Open circuit breaker listed in Step 10.

18. Reinstall P1-2472 connector on antenna valve.

19. Restore aircraft to normal operating condition.

NOTE: Steps 1 through 7 check the integrity of the VHF antenna anti-ice valve and monitoring circuit. Steps 10 through 16 check the integrity of the right wing anti-ice valve and monitoring circuit.

b. If Steps a.6 and 7 or a.15 and 16 are not satisfactorily accomplished, repair the unsatisfactory condition, or restrict the aircraft from flight in icing conditions.

c. Within one year from the effective date of this AD provide for performance monitoring of the wing and antenna anti-ice systems by separate lights in a manner approved by the Chief, Aircraft Engineering Division, FAA Western Region.

Note: McDonnell Douglas Service Bulletin 30-47 dated December 5, 1978 and/or Revision 1 dated May 22, 1979 provide a satisfactory method of accomplishment.

d. Alternative inspections, modifications or other actions which provide an equivalent level of safety may be used when approved by the Chief, Aircraft Engineering Division, FAA Western Region.

Amendment 39-3541 became effective September 29, 1979.

This Amendment 39-3603 becomes effective November 1, 1979.