2009-12 · NASA ASRS report 867743
A CRJ-200 returned back to field due to a #1 engine low oil quantity. An IDG and carbon seal replacement had been completed; but the carrier's Supplemental Procedure to perform an Oil Consumption Run had not been accomplished.
I was assigned to a CRJ -200 aircraft on a December 2009 night with Mechanic 'X' and Mechanic 'Y'. Mechanic 'Y' worked on the Service Check. Mechanic 'X' chose the left engine and I worked the right engine. I did Igniter Inspection and starter oils. I went to the left engine and helped Mechanic pull the IDG off the engine. Removed IDG carbon seal; found broken. Found carbon seal on gearbox deteriorated. Asked the Lead to please order parts for gearbox. Helped Mechanic 'X' with the IDG carbon seal. Found parts that Lead got were the wrong Modification. The parts were for a two piece pre-modification seal; which is obsolete. Reordered carbon seal and the O-ring. I know there was an O-ring in the returned seal but this is unusual. That O-ring does not usually come with the seal. I remember putting the O-ring on; but when I was installing the seal; it didn't feel springy enough so I pulled it back off. There is a Wave washer and a flat washer and an O-ring in the installation. I had inadvertently installed the Wave washer first; and then the flat; but the flat should have been first. This explained the lack of springiness. I switched them around and reinstalled the assembly. I also know I changed the carbon seal faceplate and the O-ring for that too. Then we installed the IDG. I wrote a card for the Oil Consumption Run; but the Lead brought data that said only a Leak Check was required. The data was a graph and only the Leak Check was required. We took it out for a Leak Check and ran at idle for ten minutes and no leaks were noted. I would like to know exactly which O-ring was missing.
Reporter stated the IDG was being changed because the IDG housing was cracked and leaking oil. After removing the IDG; they noticed the carbon seal needed to be replaced due to being heavily coked up and deteriorated; but the Maintenance Manual (MM) did not have any information on any carbon seals. So they went to the Engine Manual to find the carbon seal information. There was some confusion about which carbon seal and O-ring were the correct parts to install.Reporter stated he wanted to do an Oil Consumption Engine Run to verify the IDG and Gearbox carbon seal and O-ring would not leak. The Oil Consumption Run procedure involves taking the General Electric CF-34B engine to Take-off power than throttle back to 85 % sustained power. But the MM only required a Ground Run at standard idle power for ten minutes; which they did accomplish; with no leaks noted. The reporter stated even though the MM only required a standard Ground Idle run; his carrier had added a Supplemental Procedure to the MM chapter they were using for replacing the IDG and carbon seal that required an Oil Consumption Run. That procedure was added due to previous air turn backs for low oil quantity after carbon seal replacements had failed; and were not detected when using the standard Idle run. Reporter stated they have computerized Maintenance Manual that includes Hyperlinks in a Maintenance chapter they may be using for a particular job that directs them to their Supplemental Procedures. But that night; the Hyperlink system was down and the links could not be accessed. So their Lead used the MM standard idle run requirement in the MM to accomplish the Leak Check. The CRJ-200 departed and shortly after called Maintenance Control with a low oil quantity; throttled # 1 engine back to Idle and returned to field. The reporter stated Mechanics have limited access to their computerized Maintenance Manuals data and only Leads and Inspectors have the ability to reference Hyperlink additional information. Why that is; he cannot explain.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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