Narrative:

#1 engine carburetor was replaced. I was designated as the inspector on this job, another mechanic performed the work. In addition to performing this job, 1 cylinder was replaced on #2 engine, while 4 cylinders were replaced on #1 engine. When the carburetor was replaced, all work was done in accordance with the pratt & whitney R2800 maintenance manual and company work cards that systematically called out each step of the removal and replacement process. The mechanic performing the work and myself have extensive experience working with R2800's. Once I signed off the airworthiness release after complying with all necessary checks, this aircraft went on a local training flight of 2.2 hours. After meeting the aircraft after terminating its flight, no discrepancies were noted in the aircraft logbook. As a precaution, I opened both engine cowlings and visually inspected both engines. No defects were noted. The cowlings were then latched and secured. On sep/wed/02, the crew departed with the same aircraft empty and under part 91 to meet for a scheduled check ride. Shortly after departure, the captain could not lean #1 engine. He, therefore, returned to the departure airport. On meeting the aircraft, I was told of the problem. I opened #1 engine cowling and found #1 carburetor mixture control rod off the mixture control bell crank assembly. The mixture control rod end was connected and secured accordingly. This aircraft has flown a 5 hour leg without incident. I speculate the cotter key used was not appropriate for the installation.

Related reports:

Google
 

Original NASA ASRS Text

Title: A CONVAIR 340 RETURNED TO THE FIELD DUE TO INABILITY OF LEANING #1 ENG. CAUSED BY A FAILED, (PROBABLY IMPROPER SIZE) COTTER PIN ON THE MIXTURE CTL ROD.

Narrative: #1 ENG CARB WAS REPLACED. I WAS DESIGNATED AS THE INSPECTOR ON THIS JOB, ANOTHER MECH PERFORMED THE WORK. IN ADDITION TO PERFORMING THIS JOB, 1 CYLINDER WAS REPLACED ON #2 ENG, WHILE 4 CYLINDERS WERE REPLACED ON #1 ENG. WHEN THE CARB WAS REPLACED, ALL WORK WAS DONE IN ACCORDANCE WITH THE PRATT & WHITNEY R2800 MAINT MANUAL AND COMPANY WORK CARDS THAT SYSTEMATICALLY CALLED OUT EACH STEP OF THE REMOVAL AND REPLACEMENT PROCESS. THE MECH PERFORMING THE WORK AND MYSELF HAVE EXTENSIVE EXPERIENCE WORKING WITH R2800'S. ONCE I SIGNED OFF THE AIRWORTHINESS RELEASE AFTER COMPLYING WITH ALL NECESSARY CHKS, THIS ACFT WENT ON A LCL TRAINING FLT OF 2.2 HRS. AFTER MEETING THE ACFT AFTER TERMINATING ITS FLT, NO DISCREPANCIES WERE NOTED IN THE ACFT LOGBOOK. AS A PRECAUTION, I OPENED BOTH ENG COWLINGS AND VISUALLY INSPECTED BOTH ENGS. NO DEFECTS WERE NOTED. THE COWLINGS WERE THEN LATCHED AND SECURED. ON SEP/WED/02, THE CREW DEPARTED WITH THE SAME ACFT EMPTY AND UNDER PART 91 TO MEET FOR A SCHEDULED CHK RIDE. SHORTLY AFTER DEP, THE CAPT COULD NOT LEAN #1 ENG. HE, THEREFORE, RETURNED TO THE DEP ARPT. ON MEETING THE ACFT, I WAS TOLD OF THE PROB. I OPENED #1 ENG COWLING AND FOUND #1 CARB MIXTURE CTL ROD OFF THE MIXTURE CTL BELL CRANK ASSEMBLY. THE MIXTURE CTL ROD END WAS CONNECTED AND SECURED ACCORDINGLY. THIS ACFT HAS FLOWN A 5 HR LEG WITHOUT INCIDENT. I SPECULATE THE COTTER KEY USED WAS NOT APPROPRIATE FOR THE INSTALLATION.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.