Four people have been detained in connection with Thursday's suspected sabotage of industrialist Anil Ambani's chopper that he was supposed to have flown from the Mahalaxmi Race Course helipad to his office in Navi Mumbai before the incident was detected.
"We are still investigating the matter and questioning the people concerned with the helicopter's maintenance," said Senior Inspector SM Ghuge of the Santacruz Airport Police Station.
"We shall initiate appropriate proceedings, including arresting them, only after getting proper evidence," Ghuge told IANS.
Ambani didn't finally take the 20-minute flight on Thursday, a company source said, as he was tied up with a board meeting.
Later in the day, maintenance personnel discovered pebbles, small stones and mud in the fuel tank, and said if it had gone undetected, it could have led to a disaster while in flight.
"Usually, on all Thursday, Fridays and Saturdays, he (Anil Ambani) takes this chopper to fly to his office in Dhirubhai Ambani Knowledge City," the source said.
He was scheduled to leave for Navi Mumbai along with a high-level team of nine Reliance Infocomm officials in the same chopper on Friday morning. But as the chopper has been grounded till investigations are completed, Ambani took the 100-minute drive to Navi Mumbai.
The source said there were several other big and small choppers parked near Ambani's, but none was touched by the suspected saboteurs. "Apparently, Ambani's chopper was singled out," he said.
A senior official of Mumbai International Airport Ltd (MIAL) said the Bell 412 13-seater helicopter was for non-scheduled operations. "We are in no way connected with their regular operations, or any other issue," the official said.
"It is very difficult for us to say who are the persons having authorised access to such sensitive areas."
A spokesman for Air Works India Engineering, which is responsible for the maintenance of the helicopter, told IANS that a technician discovered that the chopper was tampered with after he noticed that the oil tank valve cap was not fitted properly.
The engineers then checked the helicopter to discover pebbles, small stones and mud in the fuel tank. They said if the incident had gone undetected, it could have led to a disaster while in flight.