"For example, tests of the strength and porosity of the balloon envelope have not been conducted using the equipment and techniques specified in the maintenance manual, and the engineer has relied upon individual experience and judgement instead.
"But the test has been done, nevertheless. I want to stress that.''
The 16 hot air balloons maintained by the man were owned by private operators nationwide and were effectively grounded until they were rechecked, Mr Douglas said.
"... there is doubt about their airworthiness and we want to dispel that doubt now by ensuring that those tests are redone, properly, in each of those cases,'' he said.
"They will not fly until those checks have been completely redone.''
The other 57 balloons nationwide and maintained by four separate people were free to return to the skies.
The engineer was not under any scrutiny before the accident but "will be subject to further investigation, and I'm considering at this stage further action that will result'', Mr Douglas said.
"Every participant in the civil aviation system is entitled to expect that each person carries out their functions properly and fully, and that the certifications they make are accurate, because each person relies upon that in order for the safety of the whole system.''
A spokeswoman for the company the man worked for said he was on holiday, and that it was planned leave which had been booked "for some time''.
She did not want to comment further.
TAIC last week said an examination of the Wairarapa hot air balloon accident revealed a strength test on the balloon's envelope and a fuel system inspection were not done correctly, and documentation was incomplete.
It had not determined whether or not maintenance issues were a factor in the accident, which happened at Carterton.
Those killed were pilot Lance Hopping, 53, of Masterton, husband and wife Howard (71) and Diana Cox (63) of Wellington, husband and wife Desmond (70) and Ann Dean (65) of Masterton, cousins Valerie Bennett (70) of Masterton and Denise Dellabarca (58) of Paraparaumu, partners Stephen Hopkirk (50) and Belinda Harter (49) of Lower Hutt, and Johannes Jordann, known as Chrisjan (21) of Wellington and girlfriend Alexis Still (19) also of Wellington.
