Air India RAT Reinspection: DGCA Orders Review

Mumbai, Oct 12 (PTI) Aviation safety regulator DGCA has directed Air India to reinspect the RAT (emergency power source) for stowage on all aircraft whose power conditioning module was replaced by the Tata Group-owned airline in recent times.

At the same time, the aviation safety regulator has sought a "comprehensive report" from the US aircraft maker Boeing on the preventive measures to be implemented with respect to the un-commanded Ram Air Turbine (RAT) deployment incident.

The development comes in the wake of two back-to-back incidents involving Air India 787 aircraft recently, and the pilots' grouping Federation of Indian Pilots (FIP), writing a letter to the Civil Aviation Minister, urging the government to ground Air India's entire B787 aircraft fleet, besides a special audit of the airline.

On October 4, RAT got deployed on Air India Boeing 787 aircraft, operating its Amritsar-Birmingham flight AI-117, just before the landing, while on October 9, AI-154 from Vienna to Delhi, operated by a Boeing 787 aircraft bearing registration VT-ANO, was diverted to Dubai, due to the "sudden failure of autopilot system, triggering a series of technical malfunctions".

RAT deploys automatically in the eventuality of a dual engine failure or total electric or hydraulic failure. It uses wind speed to generate emergency power.

"Air India has been advised to reinspect the RAT for stowage for all the aircraft, whose PCM module was replaced in the recent past," a senior DGCA official has said, adding that further investigation is in progress.

PCM is a crucial electrical component that converts, regulates and distributes electric power from the aircraft's power generation system to various onboard systems and equipment.

It may be mentioned here that Air India had categorically denied "any assertion that there was an electrical failure" in the Boeing 787 aircraft that was diverted to Dubai on October 9.

DGCA has also advised Air India to "review the work package of 'D' Check for the actions required in view of the change of PCM module, for any discrepancy".

During landing at 400ft, the RAT unlock message came, and it got deployed. The pilot did not report any related abnormality, and the aircraft landed safely, according to the DGCA official.

Following this, Boeing-recommended maintenance actions for uncommanded RAT deployment were carried out, and no discrepancy was observed, the official said, adding that accordingly, the aircraft was released for service and brought back to Delhi on October 5.

"Boeing has been requested to provide a comprehensive report outlining the preventive measures to be implemented in respect of the un-commanded RAT deployment incident," the DGCA official noted.

Besides, detailed information regarding similar un-commanded RAT deployments occurred globally on Boeing 787 series aircraft, as mentioned in the Boeing 787 Fleet team Digest, has also been sought from the aircraft maker, he said.

"Boeing has also been asked to provide any service difficulty report received from aircraft operators worldwide after the change of the PCM module," the official added.

Though Air India had cited "technical issue" due to which its Vienna-Delhi flight was diverted to Dubai, the FIP, in its letter to the Civil Aviation Minister, revealed that the Boeing 787 aircraft "experienced failures across critical systems, which included Autopilots, ILS (instrument landing system), flight directors (FDs) and flight control system degradation with no autoland capability".

"The pilots could not engage the autopilots due to electrical malfunctions; thus, pilots were constrained to fly manually at night and divert to Dubai. Moreover, the FDs were not available with degraded flight control systems. The aircraft landed safely at Dubai," the FIP had said in the letter, while demanding the grounding of the entire B787 fleet and a special DGCA audit of Air India.

It is also pertinent to note here that in one of the worst aircraft accidents in India, a total of 260 people, including 241 passengers, died when Air India's Boeing 787-8 aircraft operating flight AI171 to London Gatwick crashed soon after take-off from Ahmedabad on June 12.