MANDATORY MAINTENANCE ON TRANSIENT AND AVOID BANDS ON THE CRUISE GUIDE INDICATOR ON ALL CH-47D AIRCRAFT

URGENT

TB 1--1520--240--20--154

DEPARTMENT OF THE ARMY TECHNICAL BULLETIN

MANDATORY MAINTENANCE ON

TRANSIENT AND AVOID BANDS ON THE

CRUISE GUIDE INDICATOR

ON ALL CH-47D AIRCRAFT

Headquarters, Department of the Army, Washington, D. C.

3 May 2004

DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.

NOTE

THIS PUBLICATION IS EFFECTIVE UNTIL RESCINDED OR SUPERSEDED.

NOTE

MACOM Commanders may authorize temporary exception from

message requirements in accordance with AR 95-1, Chapter 6. Excep-

tion may only occur when combat operatiions or matter of life or death in

civil disasters or other emergencies are so urgent that they override the

consequences of continued aircraft operation.

Summary

a. Background --

(1) Following combat operation of CH-47D aircraft in Iraq and in the mountains of Afghanistan,

pilots reported that continuous flight operations were conducted with the Cruise Guide Indicator (CGI) in the

transient region, accompanied by excursions into the avoid region, usually encountered in turbulence.

(2) The CGI instrument provides a visual indication of loads incurred on critical dynamic compo-

nents in flight. It is divided into three bands; normal (green band), transient (yellow band), and avoid (red/yel-

low striped band). Numerous operations were reportedly conducted at high gross weights, extreme aft center

of gravity conditions, high torques, airspeeds exceeding VH, and at high density altitudes. The impact of op-

eration in the upper regions of the yellow (transient) band and any area in the red/yellow(avoid) band of the

CGI results in a significant decrease in the available fatigue life for the critical safety items on the rotor controls

and drive components. The reductions in available fatigue lives are dependent upon component loads, air-

craft loads, and the amount of time spent under these conditions.

This TB supersedes USAAMCOM Message,291515Z APR 04 CH-47-04-ASAM-02