MANDATORY MAINTENANCE FOR ALL UPPER BOOST ACTUATORS (UBA) CH-47D, CH-47F, MH-47D AND MH-47E AIRCRAFT

URGENT

TB 1-1520-240-20-163

DEPARTMENT OF THE ARMY TECHNICAL BULLETIN

MANDATORY MAINTENANCE FOR ALL

UPPER BOOST ACTUATORS (UBA)

CH-47D, CH-47F, MH-47D AND MH-47E AIRCRAFT

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

24 January 2006

DISTRIBUTION STATEMENT A:

Approved for public release; distribution is unlimited.

NOTE

This message is effective until rescinded or superseded

NOTE

This message is issued IAW AR 95-1 and has not been transmitted to units subordinate to ad-

dressees. Addressees will immediately retransmit this message to all subordinate units, activities

or elements affected or concerned. MACOMs will immediately verify this transmission to the AM-

COM SOF Compliance Officer (AMSAM-SF-A, safeadm@redstone.army.mil).

NOTE

MACOM commanders may authorize temporary exception from message requirements IAW AR

95-1, Ch 6. Exception may only occur when combat operations or matter of life or death in civil

disasters or other emergencies are so urgent that they override the consequences of continued

aircraft operation.

NOTE

Commanders unable to comply with the requirements of this message within the time frame speci-

fied will change the affected aircraft status symbol to a Red //X//.

1. SUMMARY.

a. Background. A Quality Discrepancy Report (QDR) shows that the end caps of an Upper Boost Actuator

(UBA) were inadvertently swapped (reversed). There are 4 (ea) UBAs installed on the aircraft (Forward Pivoting,

Forward Swiveling, Aft Pivoting, and Aft Swiveling Actuators). The UBAs have 2 (ea) servocylinders which are

machined with different sized return ports so that the #1 and #2 hydraulic systems cannot be crossfed into another.

When crossed, this deficiency would eliminate aircraft hydraulic system redundancy.

Message Purpose:

(1)

Require inspection of all 4 UBAs for swapped end caps.

(2)

Require removal and replacement of subject UBAs.