THE so far fruitless search for missing Malaysia Airlines flight MH370 has suffered another setback after finding out the search equipment is faulty.

The Joint Agency Coordination Centre say they have discovered a defect in the transponder mounted on Ocean Shield and that a defect may also exist in the transponder mounted on the US Navy Bluefin-21 submersible.

The Australian vessel, carrying the Autonomous Underwater Vehicle, arrived back in the southern Indian Ocean search zone on Tuesday following a port visit to Perth after the air and sea hunt was scaled back.

The plan was for it to resume scouring the seabed where transmissions believed to have come from the plane’s black box flight recorders were heard last month.

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media_camera Faulty part ... technicians tie down the Bluefin-21 autonomous underwater vehicle. Picture: Paul Kane

But the Bluefin-21 was recovered about two hours into its first mission since returning to the search area so a communications problem could be investigated.

During the recovery, Bluefin-21 was damaged but was able to be repaired expeditiously with spare parts on board the ADV Ocean Shield, JACC said in a statement today.

“Examination of the communications problem has established that a hardware defect exists in the transponder mounted on the Ocean Shield and that a defect may also exist in the transponder mounted on the Bluefin-21,” the statement said.

This inhibits the ability of the two devices to communicate with each other.”

The transponder mounted on the Ocean Shield and the transponder mounted on the Bluefin-21 communicate with each other during a dive.

When communications issues were experienced on Tuesday, the Bluefin-21 was recovered.

JACC said communication between the two devices had been working effectively up until then.

“Any communications issues previously would have been immediately obvious because communications between the two transponders are closely monitored by an operator on board Ocean Shield,” a JACC spokesperson told News Corp.

This defect also had no bearing on the signals detected by the Towed Pinger Locater, which was deployed from ADV Ocean Shield, last month.

“The Towed Pinger Locator does not rely on transponders to communicate with the operating vessel.”

media_camera Still searching ... the ADV Ocean Shield on the ocean, ready to scour for MH370. Picture: Paul Kane

Spare parts for both defects will be dispatched from the United Kingdom. The parts are expected to arrive in Western Australia on Sunday.

“Ocean Shield is currently en route to Dampier, Western Australia, to receive the transponder parts. The journey is anticipated to take a number of days,” JACC said.

“At this stage, Ocean Shield is expected go alongside so engineers can make a full assessment of the transponder repairs.”

The Boeing 777 vanished on March 8 with 239 people on board after mysteriously diverting from its Kuala Lumpur-Beijing route. It is believed to have crashed far off Australia’s west coast.

Air and sea searches over vast stretches of the Indian Ocean have failed to find any sign of MH370.

Australia, which is leading the hunt, has stressed that it believes it is looking in the right area based on satellite communications from the plane.

Officials have said an intensified undersea mission will begin once new and more sophisticated equipment to complement Bluefin-21 can be obtained to search at depths of more than 4500 metres.

The ocean bed in the prospective search zone is not just deep but largely unmapped, meaning specialist sonar equipment and other autonomous vehicles are needed.

JACC said it had now established a Military Coordination and Sub-Surface Planning Cell, led by a Royal Australian Navy hydrographer and US Navy Sea Systems Command representative.

“Preparations to conduct the bathymetric survey are continuing,” it said, referring to a study of the ocean floor terrain.

“A Chinese survey ship is now in the search area and will assist in preparations for future operations.”

Meanwhile, international experts continue to re-examine satellite imagery and all the data collated so far to try to pinpoint a more precise location for the search.

JACC said vessels from Australia, Malaysia and China and an Australian aircraft remain on standby should any surface debris need investigation.

Originally published as MH370 hits unbelievable snag