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On March 12th, I had written about the
"urgent" safety recommendations by the US National Transportation Safety Board (NTSB) regarding the Rolls Royce Trent 800 RB211 engines which are used by many Boeing 777 operators. It is estimated that there are currently about 220 Boeing 777s powered by Rolls-Royce Trent 800 engines in operation with 11 airlines around the world.
The list includes Air New Zealand, British Airways, American Airlines, Cathay Pacific, Delta Airlines, El Al, Emirates, Kenya Airways, Malaysia Airlines, Singapore Airlines, and Thai Airways.
Image courtesy Singapore Airlines
I was concerned about the impact on my favourite, Singapore Airlines (SIA), who with 77 aircraft, happens to be the world largest operator of Boeing 777s. The 777 makes up more than 75 per cent of Singapore Airlines' fleet (77 777s out of a fleet of 101 aircraft), and this will only grow as more join their fleet, and the 14 venerable
Megatop Boeing 747-400s are retired from service by next year.
SIA has 58 Boeing 777s, that are powered by Rolls-Royce Trent 800 engines. These are the 31 Boeing 777-200 (Trent 884), 15 777-200ER (Extended Range), and 12 777-300 (both Trent 892) models. 19 are 777-300ER (also called 77W) powered by General Electric GE90-115B engines, and which are used primarily in long haul flights.
I wrote to Stephen Forshaw the spokesperson for Singapore Airlines with my concerns. He has assured me and all passengers of Singapore Airlines of the airline's confidence in the Rolls Royce Trent 800 engines powering their fleet, and the short-term fix addressed by the NTSB, with training and procedures mandated the US Federal Aviation Administration (FAA), and the European Aviation Safety Agency (EASA) minimise the risk while engine manufacturer Rolls Royce rolls out the re-designed Fuel Oil Heat Exchanger (FOHE) as a longer term and more permanent solution.
He also clarified in depth about the routes that Singapore Airlines flies which are more tropical in nature when compared to the extended polar routes flown by some other airlines.
I posed to him that even Singapore Airlines flights flies polar routes. and
"with the -40 Deg and colder temperatures experienced at high altitude the route really does not have an impact on the potential for icing. i.e. whether it is a polar or tropical route."?
Stephen Forshaw explains
You are correct that temperatures can reach -40 or lower at cruise altitude, whether in the tropics or the polar region. That is not really the concern. As you would be aware, jet fuel has a very low freezing point - the variety used for commercial aircraft is Jet A1 and has a freezing point of -47 degrees Celsius. Sometimes, the temperature outside the aircraft will reach below that point, but the fuel tank ambient temperature is always higher than the outside temperature, and this prevents fuel from freezing.
Where icing potentially occurs is where the fuel has prolonged exposure to temperatures outside the aircraft at the more extreme end. [In] the BA [British Airways] case, outside temperatures for much of the polar journey reportedly reached as low as -70 degrees. The concern is the prolonged exposure to excessively low temperatures.
What is meant by my comment on the tropical nature of our operations is that, while the aircraft is on the ground, the ambient temperature very quickly warms up to a point well above zero degrees and will quickly melt any ice particles that may form. The difficulty in the BA case was that the ground temperature in Beijing was still well below zero for the entire time the aircraft was in transit. With a small number of exceptions, our RR [Rolls Royce] powered 777s tend not to operate to points where they are likely to face prolonged exposure to extreme cold conditions, both in cruise and on ground.
It would seem, from the available reports, that there were a set of circumstances that contributed to this accident; not merely that the temperature was low. Low temperatures are nothing new for jet fuel systems; it is the prolonged exposure and lack of understanding at that time of the remedial actions that we know are now necessary that are learning points. These points have all been incorporated into our procedures and pilot training, and our pilots are well aware of the issues.
In response to my query
"has any SQ B777 flight experienced an in-flight un-commanded engine roll back ?" He said
We have not experienced any similar incident, and this is possibly because, as I said, our RR-powered 777s tend not to be operating in the prolonged extreme cold conditions that the BA flight experienced. Those of our aircraft operations with prolonged exposure to polar routes are only using the B777-300ER (GE-powered) and A340-500 (RR powered but with a different fuel flow system).
To clarify, the A340-500 series used on the non-stop Singapore Los Angeles and Singapore New York service are powered by the Rolls Royce Trent 553 engines. Having flown these flights right from their inaugural, I can attest to their reliability.
In response to my queries
"on the "mood" of the airline about the Boeing 777 powered by the Rolls Royce Trent 800 RB211 engines, the fix that is being planned, and whether the recent developments will have any impact on SQs decisions on the engines for future B777 purchases ?" Stephen replied
The 777 will remain an integral part of our fleet operations for many years to come. It is an exceptionally good aircraft with a high level of reliability and customer appeal. We don't see that changing as a result of this finding, because (a) the fix developed has already been rolled out through training and procedures, and (b) RR is engaged on a longer-term redesign. I want to be clear on your question about 18 months as a time to fly with these "risks"- if there were no other mitigation measures, that would be a concern, but the procedures jointly developed and approved by the FAA and EASA provide a solution in the meantime to minimise the risk while the longer-term R&D work is done by RR.
Stephen Forshaw also confirmed that the recent developments will have no impact on the plans of Singapore Airlines to phase-out of the Boeing 744-400s by early next year.
This issue will not affect our plans to retire the B744s from service - that is a wholly different question and contingent on deliveries of newer, more fuel-efficient aircraft such as the A380 and B777-300ER.
It is clear that while the short-term training and procedural fix recommended by the NTSB, FAA and EASA is acceptable for now, it is surely not acceptable for the long term. By then Rolls Royce will have implemented the re-designed FOHE.
Would I fly aboard a Rolls Royce Trent 800 powered Boeing 777 of Singapore Airlines --
ABSOLUTELY!!!!!!!
On a side note, with the phase-out of the B744s, Singapore Airlines' long association with US engine manufacturer Pratt & Whitney will come to an end, as their entire fleet from the mighty Airbus A380 to the Boeing 777s to the Airbus A330 will be powered by Rolls Royce and General Electric engines. At one point about 10 years ago, Singapore Airlines was PWs largest customer in Asia. Singapore Airlines Cargo though, will continue using the PW4056 powered B744s.
and finally .... Stephen Forshaw is leaving Singapore Airlines for other career prospects. I wish him all success. His successor Nicholas Ionides who takes over as Vice President Public Affairs, with effect from 4 May 2009 is well known in the blogosphere. Mr Ionides, 37, is currently the Singapore-based Managing Editor (Asia) at Reed Business Information, publishers of
Flight International and
Airline Business Magazines and the Air Transport Intelligence and
Flightglobal news websites
