Aircraft News Weblog

Tag: airbus

  • PW1100G Geared Turbo Fan

    Pratt and Whitney have found themselves in a strange situation. Their order book is brimming with orders for the PW1100G ( Geared Turbo Fan) but the engine used in the Airbus 320/321 Neo is being removed in record numbers for repair. In total 1200 engines will need repairs. The problem is a number of small cracks appearing in the powdered metal used in the engines High Pressure Turbine disks that were manufactured between 2015 and 2021.

    At the moment Pratt and Whitney are producing more engines than are being removed to bring AOG (Aircraft On Ground) rates down. The defect is having an effect on multiple airlines in the busy summer season. Pratt and Whitney have increased engine production to minimize the downtime of existing customers by having engines available. Despite this, approximately 10% of the GTF fleet is parked awaiting engines. Indian airline Go First recently cited the engine as the primary reason they filed for bankruptcy.

    There are also problems with the PW1500G series engine installed in the Airbus 220. The reliability of the engine is well below the target that Pratt and Whitney expect. Some PW1524G engines in the A220-300 are being removed at less than a thousand landings instead of the forecast 5260 landings. There is an Engine Airworthiness Directive for inspection of the engine fan due to inflight shutdowns and the failure of fan blades.

    Now, in my experience there are always teething troubles with new designed engines that only appear after operational real world experience. The manufacturers do their best to cover all the bases to achieve certification from the regulator but, they can’t anticipate all the environmental affects that the engines will experience.

  • Boeing and Airbus on track?

    The Boeing Dreamliner is back in the air and the Airbus A350 is completing the first elements of the flight test program required for certification. So all is well in the Big Two manufacturers world. Or is it, such is the nature of the business that this assumption will never be accurate. There will always be setbacks and problems when each airframe, engine combination is pushing back the boundaries of fuel economy and efficiency.

    There is a huge requirement to reduce all the negatives like fuel burn and aircraft weight while increasing the load and range of the aircraft. The development of the airliner design from the first jet airliner, the De Havilland Comet, to the latest Boeing or Airbus aircraft has been amazing in the last 60 years. Every time I think they have reached the ultimate in design they exceed it with the next aircraft.

    The Boeing 737 was, and still is the work horse of the Seattle based manufacturer. It was challenged by the A320 family and now the Big Two are competing for another prize with the 787 and A350 by flying non stop from London England to Sydney Australia as a regular commercial route.

    Quite amazing that Louis Bleriot managed the first powered flight across the English Channel in 1909 and now in 2013 we are vying for non stop scheduled flights from London to Sydney.

    I can’t wait to see what they will come up with next.

  • Airbus A350-900

    A350-900

    Airbus are reporting there will be no delay to the production and testing schedule of the A350 due to the problems with Lithium-Ion (Li-on) batteries.

    While Boeing are searching for a solution with the B787 Dreamliner battery problems Airbus are pressing ahead with then A350 and have replaced the planned Li-on batteries in favour of the more common Ni-Cad type.There are a number of problems with being the ‘first’ to use new technology and Boeing have taken on the brunt of the problems with the Dreamliner.

    Airbus have been developing their own twin engined wide bodied challenger to the B777 and B787 in the A350. This is the first step into the new technology of extensive carbon fibre for Airbus who are using it as the main component in the fuselage and the wings. This will allow a fuel saving to compete with Boeing on the non stop long distance routes from Europe to Australia and New Zealand.

    Although I would need a good vacation after a London to Sydney 19 hour non stop flight. It is amazing that Bleriot only managed the first crossing of the English Channel in an aircraft from England to France in 1909, around 25 miles, and in 1989 a Qantas B747 completed a non stop flight from London to Sydney 10,500 miles as a publicity stunt.

    Something that would not have helped Bleriot is the engine developed for the A350, which weighing in at just over 6 tonnes would have been bit much for his aircraft!

    The Trent XWB-84 has completed all certification and is being shipped to Toulouse from Rolls Royce for installation. This engine will produce up to 84,000 lbs of thrust required for the first A350-900 which will be completing the flight testing of the aircraft design. Changes to the thrust of the engine will power the other two variants of the aircraft. The increased thrust for the A350-1000 will be achieved by increasing the core engine power, temperature and fan speed rather than the diameter of the engine. Due to this approach nearly 80% of the line replacement units will be common to the engine variants.

    The A350 is scheduled to start flight testing this summer and for those who would like to keep informed of developments here is a link http://www.a350xwb.com/#

  • Qantas Jet Plunges out of control. Updated

    A terrifying headline to all who fly in aircraft and it is a very real risk in the age of modern air travel. The infrequency of this occurrence is thankfully rare and the majority are weather related and avoidable.

    So, what went wrong with the Qantas Airbus A330-300 aircraft? During the flight the aircraft had several departures from its assigned altitude, the result of these changes were injuries and panic in the cabin as people who were not wearing their seat belts were thrown around.

    The majority of modern aircraft are flown by a fly by wire system; this is in response to the development of flight control computers which control the aircraft’s altitude and direction of the flight. These computers are designed to keep the aircraft within its design limits. If the aircraft is going too slow, too fast, or approaching the design limits it will take action to correct the situation.

    So, how does the computer know whats going on? There are sensors on the aircraft which measure the outside air temperature, air speed, altitude and angle of attack, (the amount of nose up or nose down), all these inputs, and many others, are sent to an Air Data Inertial Reference Unit (ADIRU) which converts them to signals for the Flight Computer so they can operate the flight controls the way the pilots require. 

    On the Qantas aircraft the ADIRU gave incorrect data to the Flight Computers which made the aircraft climb to reduce an incorrect overspeed and then dive to avoid a non existent stall due to low airspeed. The aircraft autopilot was engaged until the unexpected climb when it disconnected and the crew flew the aircraft themselves. Even though the crew was flying the aircraft the inputs from the ADIRU still continued to affect the aircraft. The design of the system is to keep the aircraft within its limits and the ADIRU was giving erroneous information to the Flight Control Computer that these limits were being approached. The effects were minimised by the crew but they were still bad enough to cause inuries to people who were in the cabin.

    This is the first known occurrence of this type of failure with the ADIRU.  Airbus have issued a Telex to all the operators of this type of aircraft to provide operational actions to minimise the effects in the event of this happening again. There are 3 ADIRU’s and 3 Primary Flight Computers on the aircraft control system and the investigation will now concentrate on how a failure with one had such an effect on the aircraft.

     

    Update

    There has been another similar incident with a Qantas Airbus A320 in the same area as the one noted above. This is an area where strong military radio transmitters are in use. There is a growing suspicion that the radio transmissions may interfere with the operation of the auto pilot. In this latest case the pilots were able to control the aircraft and return to there departure point.