AD 87-26-02 R1

87-26-02 R1 MESSERSCHMITT-BOLKOW-BLOHM (MBB): Amendment 39-5795 as revised by Amendment 39-6313. (Docket No. 87-SW-39-AD)

Applicability: Model BO-105 series helicopters, certificated in any category, equipped with main rotor blade rotating control rod ends, P/N's 105-13141.01 and 105-13142.01.

Compliance: Required as indicated unless already accomplished.

To detect and prevent fatigue cracks in the threads of the main rotor pitch links rod ends, accomplish the following:

(a) Before the first flight of each day after the effective date of this AD, check the main rotor control rods for binding of the spherical bearings as follows:

(1) Check the bearings on each control rod by rotating the rod about its longitudinal axis by hand. This check may be conducted by the pilot and must be recorded in accordance with Section 43.9.

NOTE: The pilot, when complying, must make appropriate entries and the record must be maintained per Section 91.173 or Section 135.439.

(2) Inspect and rework control rods containing a binding bearing in accordance with paragraphs (b)(1) through (b)(7) before further use.

(b) Within the next 50 hours' time in service after the effective date of this AD, conduct the following main rotor control rod inspection for cracks and spherical bearing torque determination:

(1) Remove the control rods from the helicopter.

(2) Remove the rod ends from the control rods.

(3) Measure the force required to rotate the inner race of the rod end bearings in the circumferential direction around a bolt centerline (ref. figure No.1).

(4) If the bearing torque (force X moment arm) required to rotate the bearing inner race is more than 1.5 NM (13.3 in-lbs), accomplish either of the following--

(i) Replace the affected bearing and repeat the step in paragraph (b)(3); or

(ii) Reduce the bearing friction by installing a bolt through the bearing inner race and tighten with a nut. Then, using a drill, spin the bearing at 60 to 100 RPM for 1- or 2-minute periods until friction torque is reduced to 1.5 NM (13.3 in-lbs) or below. Monitor temperature constantly to avoid overheating. (Bearing axial and radial play is not allowed.)

(5) Inspect the rod end threads as follows:

(i) Wrap the spherical bearing and rod in suitable adhesive tape to prevent cleaning solvent and wet developer from entering the bearing (ref. figure No.2).

(ii) Remove residual sealing compound, grease, and dirt from the threaded area of the rod ends.

(iii) Visually inspect the threaded area of the rod ends for corrosion.

(iv) Inspect the threaded area of the rod ends for cracks by fluorescent magnetic particle or fluorescent dye penetrant inspection methods.

(6) Replace before further flight any rod ends found to be cracked or corroded. Install serviceable parts.

NOTE: Operators are asked to submit rod ends removed as a result of this AD to MBB, DepartmentLV52, together with the helicopter serial number, flight hours, and service time, if known.

(7) Install serviceable main rotor control rods in accordance with the applicable maintenance manual instructions.

NOTE: MBB ASB No. BO-105-10-103 dated October 28, 1987, pertains to this inspection and rework.

(c) Repeat the inspections of paragraphs (b)(3) through (b)(6) after each rod end bearing replacement.

(d) Report pitch link cracks by the inspections of paragraph (b) of this AD to the Manager, Aircraft Certification Division, Federal Aviation Administration, Fort Worth, Texas 76193-0100 within 10 days of the inspection. Provide aircraft serial number, total time, and time since the last pitch link rework, if any. (Reporting is approved by the Office of Management and Budget under OMB No. 2120-1156.)

(e) Upon request of the operator, an FAA Maintenance Inspector, subject to prior approval of the Manager, Aircraft Certification Division, Federal Aviation Administration, Southwest Region, may adjust the repetitive inspection intervals specified in this AD to permit compliance at an established inspection period if the request contains substantiating data to justify the increase for that operator.

(f) An alternate method of compliance which provides an equivalent level of safety with the requirements of this AD may be used when approved by the Manager, Aircraft Certification Division, Federal Aviation Administration, Fort Worth, Texas 76193-0100 or by the Manager, Aircraft Certification Staff, AEU-100, Federal Aviation Administration, Europe, Africa, and Middle East Office, c/o American Embassy, Brussels, Belgium, APO NY 09667.

(g) In accordance with FAR Section 21.197 and 21.199, flight is permitted to a base where the inspections required by this AD may be accomplished.

This amendment (39-6313) revises Amendment 39-5795 (52 FR 46991; December 11, 1987), AD 87-26-02, which became effective on December 31, 1987.

This amendment (39-6313, AD 87-26-02 R1) becomes effective on September 26, 1989.

BEARING FRICTION MEASUREMENT FIGURE NO. 1 AD 87-26-02 R1

ROD END WITH BEARING TAPED

FIGURE NO. 2 AD 87-26-02 R1