AD 80-26-06

80-26-06 ROBINSON HELICOPTER: Amendment 39-3997. Applies to Model R-22 series helicopters certified in all categories, serial numbers 0002 through 0058.

Compliance is required as indicated unless already accomplished.

To prevent failure of the A093-2 forward tail rotor coupling flex plate and loss of power to the tail rotor, accomplish the following:

(a) Prior to further flight from the effective date of this AD, conduct a one time inspection of the A193-2 forward tail rotor coupling flex plate. Inspect in accordance with the Robinson Service Letter No. 6, dated September 24, 1980. Remove from service any flex plate found cracked, bent, nicked, or with loose clamp-up. Replace the removed part with a like serviceable part.

(b) Prior to further flight from the effective date of this AD, conduct a one time inspection of the A197-1 tail rotor drive shaft assembly in accordance with the Robinson Service Letter No. 7, dated September 27, 1980. Drive shafts withTIR (Total Indicated Runout) in excess of 0.015 inch or with excessive vibration must be removed from service and replaced with a like serviceable part.

(c) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate helicopters to a base for the accomplishment of inspections required by this AD.

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

This amendment becomes effective December 29, 1980.