56-27-01: Elevator Servo Tab Rod

56-27-01 CONVAIR: Applies to All Models 340 and 440 Aircraft. Compliance required as noted below. A report has been received concerning the failure of the elevator servo tab rod on a version of the Model 340 aircraft. Since the tabs on the subject model aircraft are unbalanced, a serious flutter condition resulted and a critical accident was narrowly avoided. In view of the fact that the tab rods and tab rod ends on the subject models aircraft are identical in design, hence susceptible to a similar type of failure, the following inspections and tab rod replacements or equivalent measures are required. Compliance required at every 110 hours of operation or regular scheduled inspection closest thereto. 1. (a) Inspect the tab rods and rod ends on the elevator, for looseness in the rivets which attach the rod ends to the rods, and for any relative movement between the rod and the rod ends. Parts which exhibit these defects shall be replaced with satisfactory parts. Upon completion of the tab rod replacement program or equivalent noted in items 2 (a), and 2 (b) below, this 110-hour inspection may be discontinued. Compliance required not later than November 30, 1957. 2. (a) Model 340 replacement of all elevator tab rods with improved, heavier rods and rod ends, and replacement of the right-hand elevator tab idler link with symmetrical idler link. (Convair Service Bulletin Nos. 340-207 and 340-150A cover this same subject.) 2. (b) Model 440 replacement of the right-hand elevator tab rods and tab rod ends with improved heavier tab rods and tab rod ends. (Convair Service Bulletin No. 440-27A covers this same subject.)