WHE

Crane Safety Advisories

1. BACKGROUND

A. The purpose of this CSA is to inform activities of a known design deficiency of JR Merritt controllers utilizing a BH-11 handle. If the dead-man switch on the handle of the affected controller is too tightly pressed, the possibility exists that the micro-switch and deadman switch relay would drop out and stop the affected controller motion unintentionally. Reference A displays the old version of the BH-11 handle side-by-side with the newer version, and reference B displays the redesigned version. Newer designs of the JR Merritt contain an updated design of the deadman switch lever that has a raised portion on the end of the lever which acts as a bumper or travel stop when the lever is depressed.

B. The affected products are the BH-11 JR Merritt controllers manufactured on or before 2011

2. DIRECTION

A. Within the next 180 days, activities shall review their inventory to identify JR Merritt BH-11 handles manufactured on or before 2011 and inspect them for the components outlined in references A and B.

Affected cranes shall be tagged with an information tag, notifying the operator of this condition until the JR Merritt controllers can be replaced.

B. Activity's shall follow reference C requirements when tagging out equipment, and replacing controllers.

1. Background:

A. The purpose of this CSA is to provide revision to the testing instructions directed by Ref (a) and provide additional time to perform the new instructions as directed.

B. Ref (a) informed activities of an operational deficiency on rotate and travel functions on some Samsung 60-ton and 151.1-ton portal cranes and Westmont 60-ton portal cranes using Emerson Mentor drives. An activity recently reported that on two different cranes the drive moved the function slowly in the opposite direction from which it was operated. This occurred when the function master controller was moved slightly from the neutral detent position providing the drive with a directional contacts command and a speed reference of zero. Further investigation has identified a biased open loop voltage feedback from the armature, providing the drive with a non-zero voltage signal when not moving. The drive interpreted this signal as motor movement, and applied a corresponding voltage to the armature causing the signal to zero out, which resulted in motor movement.

2. Direction:

A. Within 30 days of issuance of this revised CSA, activities with Samsung 60-ton and 151.1-ton portal cranes and Westmont 60-ton portal cranes utilizing Emerson Mentor drives for rotate or travel functions shall operationally test the rotate and travel functions to ensure that they do not operate in the wrong direction when the master controller is placed just outside of neutral. This check is to be performed by utilizing a computer or drive keypad display to monitor the master switch reference as compared to a motor drive shaft (or commutator) using the testing instructions in 2B.

B. In order to test for appropriate motor rotation, use the drive keypad display or connect a computer to monitor the PreSpeedRef1 variable (master switch reference) and remove any covers necessary to allow viewing of the commutator or motor coupling. Adjusting the value of RefInMin in accordance with the requirements of Ref (b) paragraph 6.4.5.d is acceptable to facilitate performance of this test.  Operate the function by cracking the stick to a position where the PreSpeedRef1 variable is less than the RefInMin variable, which will cause the output of the scaling block to output the RefOutMin value. After any initial torque proving sequence, observe the motor commutator -no sustained motion should be occurring in the unintended direction. Repeat the test in both directions and in both 25% and full speed for all rotate and travel functions using Emerson Mentor drives.

C. If sustained motion is observed at the motor commutator or shaft in the unintended direction for any of the tests, then the crane shall be removed from service immediately, and the results will be reported to NCC. If it is determined by NCC that the movement is attributable to speed reference biasing, an alteration of the drive parameters implementing a minimum speed that prevents the drive from relying on voltage feedback to maintain a zero speed when the brakes are released shall be submitted to Navy Crane Center in accordance with section 6.2 of Ref (a) prior to returning the crane to service.

D. Results of operational testing are to be reported for all cranes tested to the POC listed above. This operational testing will be evaluated for revision of this CSA or other Navy Crane Center direction.