AD 74-17-05 ACTIVE

74-17-05 GRUMMAN AMERICAN AVIATION CORPORATION: Amendment 39- 1920 as amended by amendment 39-2263 is further amended by Amendment 39-2359. Applies to Grumman Model G-1159 airplanes certificated in all categories.

Compliance required within the next 10 hours' time in service after receipt of telegram dated July 17, 1974, unless already accomplished or noted otherwise. Any equivalent method of compliance with this AD must be approved by Chief, Engineering and Manufacturing Branch, FAA, Southern Region. Deactivate the ground spoilers by accomplishing the following:

1. Remove the electrical connector on the ground spoiler solenoid operated control valve P/N 1159 SCH 230-1. Cap and stow. Placard control valve "INOPERATIVE".

2. Pull and lock out ground spoiler circuit breaker (2 amp) (Pilot's Circuit Breaker Panel).

3. Disconnect the ground spoiler actuators from the solenoid actuated control valve by either of the following methods:

1st METHOD

(A) Removehydraulic line P/N 1159H20014-770 GRSU-6 which connects the ground spoiler control valve to hydraulic flow divider P/N 1159 SCH 255-1.

(B) Remove AN815-6 union from flow divider. Remove restrictor-filter P/N H962-041 from the control valve and install in open port of flow divider using P/N 1159H20011- 6 O-ring. Leave port open to atmosphere. Plug open port of control valve with P/N AN814-6DL plug and P/N 1159HZ0011-6 O-ring. Safety plug.

(C) Plug both ends of line removed and place line and union in storage, OR

2nd METHOD

(A) Disconnect restrictor-filter P/N H962-041 from the control valve. Leave restrictor-filter attached to the hydraulic line P/N 1159H20014-770 GRSU-6 and open to the atmosphere. Secure the hydraulic line and restrictor-filter.

(B) Plug the control valve with P/N AN814-6D plug and P/N 1159H20011-6 O-ring.

4. Without hydraulic system pressure applied, check that the ground spoiler cylinders are locked. This may be accomplished byapplying an upward force of approximately 50 pounds to the trailing edge surface of the ground spoiler. There shall be no motion of the cylinder piston. If the piston extends, readjust the cylinder terminal end until a locked condition results.

5. Repeat item 4 with "Combined" hydraulic system pressure applied.

6. Install following placard adjacent to the Ground Spoiler Hydraulic Pressure Arming Switch with the words "GROUND SPOILERS INOPERATIVE".

7. To prevent the Speed Brake/Take-Off warning from sounding during landing incorporate Grumman Interim Aircraft Service Change (ASC) 181 "Speed Brake/Flap Warning - Ground Disable" by September 13, 1974.

The "NO GRD SPOILER" light will be inoperative.

8. Follow the Airplane Flight manual procedures for selection of ground spoiler switch, "armed" for take-off, to prevent hydraulic system pressure fluctuations in the event of failure of the left engine during take-off.

For flight operation with the ground spoilers inoperative, attention is directed to the following limitations in the AFM:
Page 1-9, Anti-Skid Brakes. The airplane will not be dispatched with the anti- skid system inoperative.
Page 1-10, Takeoff with 10 degree flaps. No takeoff will be made when using 10 degree flaps.

Page 1-27, Note at bottom of page. Add 680 feet to the required field length or subtract 680 feet from the available field length in determining allowable weight.

Landing field lengths in AFM are unchanged - See AFM Page 4-126.

In order to reactivate the ground spoilers, Grumman ASC 180 - Flight Controls (ATA No. 27) "Reactivation of Ground Spoilers" or equivalent approved by Chief, Engineering and Manufacturing Branch, Federal Aviation Administration, Southern Region, must be complied with.

Amendment 39-1920 was effective August 9, 1974, and was effective on receipt for all recipients of the telegrams dated July 17, 1974, and July 25, 1974, and the letter of July 29, 1974, which contained this amendment.

Amendment 39-2263 became effective on July 18, 1975.

This amendment 39-2359 becomes effective September 1, 1975.