Pilot reported an aircraft had many problems that were not previously diagnosed correctly or properly repaired. Reporter stated the aircraft was grounded for further repairs.

Narrative

New aviation department manager came out of retirement to assist nonprofit; charity in all aspects of aviation safety. This aircraft had multiple accidents in years past that nobody took the time to properly diagnose and find the root issues. This managers experience is what found precisely why there were so many problems that were being misdiagnosed by mechanics; avionics techs. and I/As. Once the root cause was found the aircraft was put into AOG status. ' Not flyable Until investigated; And-repaired'. The local FSDO office was contacted and aviation specialist in accelerated stop and post accident forensics could be accomplished. Damages were found after years of hidden problems to include NAV; COM; electrical; structural; antennas; damages. The aircraft is still being disassembled; meticulously and finding multiple issues-that this aviation department manager has seen in his XX years in aviation. That being said; the logbooks are being investigated; and all previous work is being scrutinised. This aviation department manager will be an expert witness amongst many pillars of the aviation community that are staunch stickers for safety. the whole story of what damages there are to the aircraft still not all found at the writing of this report. Additional issues will be addressed in the future.