AD 89-21-01

89-21-01 SOCIETE NATIONALE INDUSTRIELLE AEROSPATIALE (SNIAS): Amendment 39-6562. Final copy of priority letter AD. Docket No. 89-ASW-53.

Applicability: AS 350 and AS 355 series helicopters, all serial numbers, containing M/R swashbearing assemblies, Part Number (P/N) 704A33 651.126 (bronze cage), or P/N 704A33 651.009-.051, or .080 (composite cage), certificated in any category.

Compliance: Required as indicated, unless already accomplished.

To prevent failure of the M/R swashplate bearing, and possible loss of the helicopter, accomplish the following:

(a) Within the next 10 hours' time in service after receipt of this AD, inspect the bearing for play or binding; measure the swashplate rotational torque; inspect for proper assembly of the bearing; and inspect for proper lubrication, in accordance with the following:

(1) Check for play and hard points (ref. paragraph 5.2.b of Aerospatiale MET Work Card 62.30.00.601).

(2) Check the star bearing rotational torque as follows:

(i) Rotate the star manually approximately 10 times.

(ii) Using a spring scale hooked onto the pitch change rod attachment point, check that the load "C" (see figure 1) required to rotate the star is equal to or less than 2.5 daN.

(iii) If "C" is greater than 2.5 daN, replace the bearings before further flight.

(3) Check that the bearing is correctly installed as follows:

(i) Remove the bolts and nuts while retaining the deflector or baffles (see figure 1) and stops.

(ii) Move the deflector or baffles, the bearing inside stop, and the outside stop upwards.

(iii) Check that the plates that immobilize the bearing inner and outer races are seated correctly against the upper faces of the stationary and rotating stars.

(iv) Check that the dimension "L" (see figure 1) bearing inner race protrusion is above the star upper face and is equal to or less than 2.5mm. If "L" is greater than 2.5mm, replace the bearing before further flight.

(4) Check the bearing grease as follows:

(i) Install inner bolts to prevent grease from egressing through bolt holes and inject grease through the greasing nipple located beneath the stationary star, until the grease comes out.

(ii) Repeat the greasing operation three times, turning the star through 180 degrees between each operation.

(iii) Recover the grease evacuated and visually check to see that it does not contain bronze particles (bearing P/N 704A33 651.126) or composite material particles (for bearing P/N's 704A33 651.009-.051 or .080). A blackish coloring of the grease is acceptable.

(iv) If bronze or composite material particles are found, replace the bearing before further flight.

(b) Repeat the inspections of paragraphs (a)(2) and (3) of this AD after each replacement of the swashplate bearing.

(c) Within every 100 hours' additional time in service after compliance with the requirements of paragraph (a) of this AD, repeat the lubrication requirements of paragraph (a)(4) of this AD.

(d) Within the next 400 hours' total time in service from the effective date of this AD, plug the nonrotating swashplate vent holes and barrel nut orifices in accordance with the following:

(1) Remove the main rotor mast (ref. MET Work Card No. 62.30.00.401).

(2) Remove and disassemble the swashplate (ref. MRR Work Card No. 62.30.00.702, Replacement of Swashplate Bearings).

(3) On the nonrotating swashplate--

(i) Blank off the vent holes opposite the nonrotating scissors yoke (see figure 1A) with "DEVCON F" (as directed in the instructions provided with this product);

(ii) Blank off the bushing holes using "DEVCON F" (same procedure); and

(iii) Clean the areas to be coated with "DEVCON F" thoroughly with Trichlorethylene, making sure all traces of grease are removed.

(4) Assemble the swashplates (ref. MRR Work Card No. 62.30.00.702).

(5) Grease the bearing (ref. MET Work Card No. 12.00.00.305).

(6) Assemble the rotor mast (ref. Work Card No. 62.30.00.401).

(e) In accordance with FAR Sections 21.197 and 21.199, the helicopter may be flown to a base where the inspections required by the AD may be accomplished.

(f) An alternate method of compliance with this AD, which provides an equivalent level of safety, may be used if approved by the Manager, Rotorcraft Standards Staff, ASW-110, Federal Aviation Administration, Southwest Region, Fort Worth, Texas 76193-0110.

This amendment (39-6562, AD 89-21-01) becomes effective on May 3, 1990, as to all persons except those persons to whom it was made immediately effective by Priority Letter AD 89-21-01, issued on October 6, 1989, which contained this amendment.