By Tim Hepher
PARIS (Reuters) - Airbus
The problems are related to the hydraulic systems and particularly an increased noise when taxiing, they said, adding that some jets are also displaying excess hydraulic temperatures, which can be a nuisance in hot climates.
Speaking separately in Dubai, Qatar Airways Chief Executive Akbar Al Baker said the aircraft had issues "with the hydraulic system and the software". [L5N17S3NK]
Airbus reiterated that any glitches would be resolved by July.
Regular flyers are familiar with the distinctive "dog bark" sound heard below the cabin in some Airbus jets before take-off.
The sound is produced by a pump designed to maintain equal pressure in separate hydraulic systems, even when one of the engines supporting them is shut down.
It is a safety feature designed to ensure there is enough hydraulic pressure to retract the landing gear quickly in the event that one engine fails on take-off -- something needed to reduce drag and allow the pilot to execute a smooth recovery.
But the sound is particularly noticeable when the aircraft is taxiing on one engine, which many airlines do to save fuel.
In some of the new A320neo aircraft, that sound is more noticeable and it is feared this could be disturbing to passengers, said two people familiar with the matter.
A source close to Indian budget carrier IndiGo said noise was not a problem and the airline continued to take deliveries.
Until now, publicity surrounding A320neo deliveries has focussed on problems with engines made by Pratt & Whitney
The A320neo is also offered with LEAP engines from General Electric-Safran
Two industry sources said a key part -- the low-pressure compressor or "booster" -- is being modified after a problem in testing. Routine changes in engine architecture at this stage of development are considered relatively rare, they said.
A CFM spokeswoman denied there are any problems and said the changes are to improve durability by allowing more flying time between major overhauls.
The changes will not affect targets of 15 percent lower fuel consumption, she added.
The first CFM-powered Airbus A320neo will enter service in July with Turkey's Pegasus Airlines, industry sources said.
The redesigned engine part will be included from the outset in Boeing 737 MAX jets due to enter service in 2017 and may be retrofitted during scheduled overhauls for early Airbus users.
(Additional reporting by Tommy Wilkes, Matt Smith; Editing by Mark Potter and David Goodman)
