He however admitted that there were some irregularities in the procurement process.
In a query letter sighted by Luv News in December last year, the board claimed Noble Appiah had defied the board in the award of contracts and staff recruitment without approval, including other breaches.
An audit by PKF covering the period between July 2013 and June 2014 already raises questions about procurement irregularities against Mr Appiah.
He is found to have spent over GHC33 million without approval for which the board is demanding answers.
A letter dated September 29, 2014 is signed by Chairman, Osaberimah Ansah Sasraku and copied to the Transport Minister, cites Mr Appiah for defying the board’s directives to award tender for supply of 400 tyres valued at GHC604, 800 to Allied Home Stores, instead handing the deal to Rana Motors.
That happened after a warning letter to the MD for earlier breaches for which MR Appiah apologised.
The board also alleges that while the MD awarded the contract to Rana Motors on July 22, 2014, he communicated continued negotiation with Allied Home Stores to the board on August 22, 2014.
The same memorandum dated March 13, 2014, on the purchase of the 400 tyres was used again on March 31, 2014 to purchase an additional 500 tyres.
The query letter indicated that the MD implemented the 2014 procurement plan before presenting it to the board.
It refers to an advertisement in the March 25, 2014 edition of the Ghanaian Times on tenders for procurement of items in the 2014 plans the same day it was submitted to the board for approval.
According to the board, Mr Appiah engaged in operational staff recruitment without the board or the Transport Ministry’s approval of buses due to be imported from China though the deal was yet to be completed.
Mr Noble Appiah was investigated following a petition by the Junior and Senior Staff Association of the company asking that management and the Transport Ministry investigate the mysterious disappearance of some buses owned by the company last year.