AD 81-22-51

81-22-51 BOEING: Amendment 39-4291. Applies to all Boeing Model 747 series airplanes certificated in all categories with Rolls Royce RB.211 engines. To alert the flight crew to conditions which may precede engine failure, perform the following, unless previously accomplished:

A. Within 25 hours time in service after the receipt of this AD, or within 3 calendar days, whichever occurs later, revise the Boeing 747 FAA approved Airplane Flight Manual to add the following and provide to the flight crew:

SECTION 1 - LIMITATIONS

Powerplant Limitations

Airborne Vibration Monitor (AVM) System

o At least one channel (A or B) of the AVM system must be operative for each engine for all flight operations. o The operative AVM channel (A or B) must be the same for all engines. o When both channels of the AVM system are operative, select channel A. If this channel becomes inoperative (indication goes to zero) in flight, select B. o The AVM filter selector must beset to the norm position at all times except during routine AVM monitoring checks.

SECTION 2 - EMERGENCIES

Engine Abnormal Vibration Indication

During steady running conditions, if an airborne vibration monitor (AVM) system channel indicates a sudden increase of 1 (one) unit or more, or if the AVM warning light activates, even if the indicator returns to normal:

IMMEDIATE ACTION

THRUST LEVER CLOSE START LEVER CUT OFF

NOTE: During takeoff roll, a momentary fluctuation of the AVM indicator with no other indication of engine malfunction is not cause for shutdown.

NOTE: When holding or descending in severe icing conditions, the AVM indication may gradually increase to above 2.5 units (warning light setting). This condition can be alleviated by increasing N1 to 90% for 5 seconds when ice accumulation (gradual vibration increase) is first detected. AVM indications may exceed 2.5 units during shedding. No action is required unless other indications ofengine malfunction are observed.

SECTION 2 - EMERGENCIES Engine Oil Light Illuminated If the engine oil light illuminates steadily or filter blockage is indicated:

IMMEDIATE ACTION

THRUST LEVER CLOSE START LEVER CUT OFF

B. Within 60 days calendar time after effective date of this AD, install an amber repeater light (annunciator) for the vibration meter alarm lights on the pilot's panel in accordance with Boeing Service Bulletin 747-77-2061 dated November 4, 1981, or later revision approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Mountain Region.

C. When the indications specified in paragraph A above occur, engines must undergo the following maintenance actions prior to further engine operation for flight:

1. Rolls Royce RB.211-77-A6424, Rev. 1, dated October 14, 1981, paragraph D.(4) for oil pressure and/or AVM indications. 2. Boeing Maintenance Manual Chapter 71-00-47, High Indicated Vibration.

D. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD.

E. Alternate methods of compliance with this AD may be used when approved by the Chief, Seattle Area Aircraft Certification Office, FAA, Northwest Mountain Region.

The manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to the address listed above. These documents may also be examined at FAA Northwest Mountain Region, 9010 East Marginal Way South, Seattle, Washington 98108.

This amendment becomes effective January 11, 1982, and was effective earlier to those recipients of telegraphic AD T81-22-51 dated October 16, 1981.