I have encountered exactly the situation you described. I spent 30 minutes with NG benefits, and they transfered me to Metlife. Spent 30 minutes with Metlife benefits, and they transferred me back to NG. Another 30 minutes with Metlife and back to NG. This time, NG instructed me to write letters to NG Benefits and Metlife Bookkeeping and to enclose a copy of my TRW/AETNA certificate. These letters were posted this pm to:
Northrop Grumman Benefits, P. O. Box 770003, Cincinnati, OH 45277-0065 and Metlife Bookkeeping, P. O. Box 14401, Lexington, KY 40512-4401. Neither entity were able to find my certificate, or for that matter any record of my name or SSN. I retired from the TRW INC Electronics and Defense in 1988.

In 2006 I got a 2006 Summary Annual Reports from NG. Talked with them at that time (800-894-4194) and they agreed that they held my certificate and my file.

My certificate reads “TRW INC Electronics and Defense”. What did or does yours read.
The reason I ask is because it is my understanding that not all of TRW ended up with NG, such as the automotive parts.
Sincerely, Lucian V. Franklin Jr