AD 90-26-11

90-26-11 BELL HELICOPTER TEXTRON, INC. (BHTI): Amendment 39-6840. Docket No. 90-ASW-15.

Applicability: All Bell Model 212 helicopters, certificated in any category.

Compliance: Required as indicated, unless already accomplished.

To prevent fatigue failure of the main rotor drag brace assembly which could result in loss of control of the helicopter, accomplish the following:

(a) Within the next 100 hours' time in service after the effective date of this AD, determine if drag brace assemblies, part numbers (P/N) 204-011-140-003 or -005, are installed in the main rotor hub assembly, P/N 204-012-101-009. For helicopters equipped with drag brace assembly, P/N 204-011-140-003 or -005, comply with the requirements of paragraph (b).

(b) For main rotor hub assemblies, P/N 204-012-101-009, with 1,200 or more hours' time in service, since new or since the last overhaul, comply with the following within the next 100 hours' time in service after the effective date of this AD. Thereafter, comply at intervals of 1,200 hours' time in service from the last inspection-

(1) Remove the main rotor drag brace assemblies, P/N 204-011-140-003 or - 005. Inspect for corrosion and mechanical damage. Magnetic particle inspect all parts (as specified in BHTI Component Repair and Overhaul Manual, BHT-212-CR&O-1);

(2) If cracks are found, or if corrosion or mechanical damage is present which cannot be removed within the rework limits of BHT-212-CR&O-1, replace with serviceable parts; and

(3) Assemble the drag brace assemblies as specified in BHTI Component Repair and Overhaul Manual, BHT-212-CR&O-1, with the following additions:

(i) Apply a soft film corrosion preventive compound to the barrel threads prior to assembly.

(ii) Install the drag brace assemblies and torque the locking nuts to 275-325 foot pounds.

(iii) After first flight confirm the torque of 275-325 foot pounds and apply a hard film corrosion preventive compound to the exposed threads.

(c) An alternative method of compliance, or adjustment of compliance times, which provides an equivalent level of safety, may be used when approved by the Manager, Rotorcraft Certification Office, ASW-170, Federal Aviation Administration, Fort Worth, Texas 76193-0170.

(d) Bell Helicopter, Inc., Alert Service Bulletin 212-90-59, dated February 5, 1990, provides an acceptable means of compliance with this AD.

This amendment (39-6840, AD 90-26-11) becomes effective on January 18, 1991.