Posts Tagged ‘European Aviation Safety Agency’

Rolls Royce scrambling to find Trent 900 replacement engines

November 17, 2010
Mechanic working on a Rolls Royce Trent 900 en...

Trent 900: image via Wikipedia

Rolls Royce is asking Airbus to return new engines destined for new aircraft so that they can be supplied to Qantas, Singapore Airlines and Lufthansa for their operations. This in turn is having a knock-on effect on future A380 deliveries.

In the meantime Qantas seems to be having a rash of minor issues which have caused aircraft to return after cockpit fires, bird hits and lightning strikes.

The European Regulator (EASA) has not commented on why they relaxed their Airworthiness Directive and whether this was done in response to representations from Rolls Royce. The engine maker is also silent on whether they knew of the Trent 900 problem and the risk for an engine fire prior to the uncontained explosion of an engine on QF32.

Reuters reports on the logistics problems faced by Rolls Royce:

British enginemaker Rolls-Royce has asked Airbus to return Trent 900 engines from A380 superjumbo production lines so they can be used to replace faulty ones on aircraft already in service.

The Airbus A380 — the world’s largest passenger aircraft with an average list price of about $350 million — has been hit by safety concerns after a Rolls-Royce engine partly disintegrated mid-flight, forcing a fully laden Qantas plane to make an emergency landing in Singapore on Nov 4.

Rolls-Royce’s move could be another blow to a much-delayed A380 program as Airbus was scheduled to deliver over a dozen Rolls-Royce-powered A380s — primarily to Singapore Airlines, Qantas and Lufthansa by the end of next year.

“Until this problem is fully resolved I think the situation with the delivery of A380 to customers … will be in jeopardy,” Standard & Poor’s analyst Sukhor Yusof said. But both Singapore Airlines and Qantas, with a combined 22 A380s still to be delivered, said on Tuesday they had not been informed of any delivery delays.

Airlines using the Rolls-Royce Trent 900 engines have been ordered by European aviation authorities to undertake major tests, which analysts said were so strenuous they would likely disrupt schedules.

“I can confirm that Rolls-Royce is arranging to supply some new engines from the production line to replace some engines removed from the serviced aircraft,” an Airbus spokesman in Singapore said, without saying which airlines would receive those engines.

Shares in Rolls-Royce, which on Friday said fixing the fault would lead to only slightly slower profit growth, have suffered during its probe and were 0.2 percent down at 596.50 pence by 1130 GMT on Tuesday, around 9 percent below their last trade before the Qantas incident. Airbus parent EADS has lost 5 percent since the incident and hit a one-month low on Monday. Its shares were 1.3 percent down at 17.78 euros. Qantas is down 4.9 percent since the incident. Airbus said last week that the problem with the Rolls-Royce engine could have an impact on its earnings and delivery target for 2011 but did not give details, and airlines contacted on Tuesday had no knowledge of delivery timetable changes.

Problem with Trent 900 was known before accident and raises ethical questions

November 15, 2010

The diagnosis of the problem with the Trent 900 has come in a matter of days and the solution has already been identified and is under implementation. This convinces me that the problem was already known and so was the solution.

There are at least two  important ethical questions which are raised by the Trent 900 story.

1. The European Aviation Safety Agency (EASA), in August, apparently  relaxed a directive regarding the frequency with which Trent 900 engines were to be inspected. The Directive had been issued originally in January. That in itself  should primarily be a technical judgement call and judgements – especially in hindsight – can always be found to be faulty without raising any issues of ethics. However the ethical issue arises if – as it seems to be – the relaxation in August was initiated by representations from a party (Rolls Royce in this case) who found the original directive too onerous. The ethical standards of both the Regulator (EASA) and of the petitioner (Rolls Royce) then give cause for concern.

2. The second ethical issue arises if Rolls Royce knew in advance of the accident to the engine on QF32 that the engines in use were at risk and that the consequences could have been catastrophic. If this was just a judgement of the probability of failure and that this probability was judged insignificant then it is an issue of bad judgement but not unethical. But an insignificant probability of failure should not have initiated the programme of engine modifications that was apparently ongoing even before the accident. Therefore, if Rolls Royce, knowing full well that the risks were sufficiently high to require that the engines had necessarily to be rectified, kept quiet in the “gamble” that no accidents would occur before they had managed to modify all the “faulty” engines,  then it becomes a case of low ethical standards and not just poor judgement. Reports suggest that Rolls Royce knew that the modifications were necessary more than a year ago but also that the mechanic who revealed this was forced to speak anonymously. This does not give any confidence that there is full transparency and, in fact, strengthens the view that Rolls Royce knew there was a problem. The speed (days rather than months) with which the diagnosis has been made and the solution defined also indicates that the engine failure did not come as much of a surprise and that the problem and the solution were already known.

The mainly technical issues with the engine indirectly raise a more general question for the aviation industry of whether there are conditions where competitive pressures  can be damaging because they increase the risk of potential harm to the general public (who unwittingly become guinea pigs for testing new technologies).

Did Rolls Royce know about the risk for a Trent 900 failure before the Qantas accident?

November 14, 2010

Another new twist to the Rolls Royce Trent story.

First it appears that the regulators (EASA) relaxed their original inspection requirements in their Directive of August. It is not clear if this relaxation was in response to the airlines or to the engine maker requesting a change.

Now it seems that Rolls Royce may well have known (perhaps a year ago) that a number of their engines on “older” A 380s were susceptible to oil leaks and therefore to the potentially catastrophic consequences of a fire. About 40 engines on the Qantas, Singapore Airlines and Lufthansa A 380s have to be changed out.  The newer engines have undergone two modifications compared to the older engines. It seems that Rolls Royce started modifying oil systems on some engines almost a year ago.

If Rolls Royce knew about the risk to the Trent 900 before the flight of Qantas QF32 on November 4th, there is an ethical dimension which needs to be considered.

According to the Herald Sun,

Fourteen of the 24 Trent 900 engines fitted to the six A380s Qantas has grounded are suspected of having an oil leak problem. Another 24 “faulty” engines are on Singapore Airlines jets. The airline has grounded three A380s. Two have been found by the German carrier, which has suffered two Trent incidents.

Revised versions of the engine are being rushed to Qantas.

Sir John Rose, chairman of the British engine maker, issued a statement late on Friday in which he admitted a “specific component in the turbine area of the engine caused an oil fire”, which led to a turbine disc hurtling out. He offered “regret” for causing “disruption”. But he failed to reveal when Rolls-Royce discovered the turbines of the Trent 900 were being exposed to the dangerous oil leaks and the dates of the two upgrades.

Qantas, Singapore Airlines and German carrier Lufthansa installed the original-spec engines on some of their jets. It is understood Qantas has begun record checks to see whether Rolls kept its engineers informed of the design changes to the $25 million engines.

An aircraft mechanic with one of the three airlines claimed Rolls-Royce began modifying the oil lubrication system on the Trent 900 engine in the second half of last year.

Trent 900: European Aviation Safety Agency (EASA) relaxed earlier directive and reduced inspection frequency

November 13, 2010

Now that it seems that the main cause of the uncontained failure of the Trent 900 on Qantas Airbus QF32 has been diagnosed, and that a remedy is being implemented, attention is turning to the Regulators.

In September the FAA issued an Airworthiness Directive (AD) for the Trent 900 based on an AD issued in August by the European Aviation Safety Agency (EASA). Since the incident EASA has now issued an Emergency AD regarding the inspection of wear within the Trent 900.

Yesterday  Joerg Handwerg, a spokesman for the pilots’ union for Lufthansa said that minor problems are routine for any jet engine, but it is possible that the issues were an indication that regulators did not adequately check the engine before approving it for commercial use. “When you see we have a problem with not just one of these engines but several then it points towards that we have a problem in the certification process,” Handwerg said.

Today Business Week (carrying an AP report) writes that “Air agency issued engine warning then eased checks”

Three months before a superjumbo jet engine blew apart and forced an emergency landing, European safety regulators had relaxed their inspection order for the same section of the engine implicated in the dangerous mishap. In January, the European Aviation Safety Agency required airlines to inspect for wear on the shaft that holds one of the Rolls-Royce Trent 900 engine’s turbine discs. The more wear they found, the sooner future inspections would be required.

In August, after Rolls-Royce had inspected several engines, EASA revised its directive. Previously, airlines had to calculate how worn out the part was based on the worst spot. Under the revised directive they calculate the average wear over the entire part. And previously they had to assume the part was wearing out at a worst-case rate. The new rule allows them to calculate the wear rate on each engine. That meant less frequent inspections, which the revised directive said were “sufficient to prevent unacceptable wear.”

The implication here is that the airlines (or Rolls Royce) were finding the inspection regime onerous and EASA responded by rationalising the change to base the frequency of future inspections on “average” wear rather than the “worst case wear” observed. Inspections of course require skilled resources, cost money and increase the down-time of aircraft. It becomes essentially an issue of operational cost. EASA – like all regulators – has to walk the tightrope balancing between public safety interests and the airlines’ need to keep costs reasonable.

Business Week continues that EASA apparently avoided the use of the word “uncontained” in its AD whereas the FAA Directive was more sharply worded:

The European directives warned of the potential for “in-flight shut down, oil migration and oil fire.” The U.S. Federal Aviation Administration went further in adopting a version of the European directive in September, warning of an “uncontained failure of the engine, and damage to the airplane.” Some of the parts inside jet engines rotate faster than the speed of sound. Engines are designed so that even if part of one shatters, pieces of metal aren’t sent rocketing away from the engine. An “uncontained engine failure” with shrapnel-like engine pieces that can damage other parts of the plane is both rare and extremely dangerous.

That’s what happened Nov. 4. Investigators have said that leaking oil caused a fire in the engine of a Qantas A380 that heated metal parts and made the motor disintegrate over Indonesia last week before the jetliner returned safely to Singapore. Experts say the mishap damaged vital systems on the plane, which had been bound for Sydney.

The safety order wasn’t addressing the exact same problem that caused the Qantas engine to disintegrate, but is very similar and involved a turbine next to the one that broke apart, said Chuck Eastlake, a former professor of aerospace engineering at Embry-Riddle University in Daytona Beach, Fla.

The decision to relax the EASA order was likely based on inspections that gave engineers confidence that the wear on parts that could cause an oil leak was predictable enough to allow more time to elapse, Eastlake said. In hindsight that appears not to have been the case, he said.

“That kind of stuff is always a judgment call based on experience,” Eastlake said. “It’s hard to specifically justify a decision like that because it isn’t a matter of plugging numbers into a calculator and out comes an answer.”

John Cox, an aviation safety consultant and former airline pilot, said it’s a question of balancing “what is reasonable to ask the airlines to do against safety. The problem is we had a catastrophic failure. It turned out that apparently at least one engine had substantial wear that inspections didn’t pick up,” he said in a telephone interview from London.

No one from EASA was available to talk about the directive late Friday.

The different communications strategies used by the players involved have varied greatly. Rolls Royce have said remarkably little and even their latest statement was baked into a Trading Report for investors. In such a report the objective is to reassure the audience so that share price holds up and doesn’t crash. The conclusions – in consequence – have to be tailored to these objectives.  In this case the focus was on showing that while there will be some costs, profits for the year will not be hit too hard. Investors – and not passengers – were clearly the audience for this Rolls Royce communication and that is of some concern.

The other players – the airlines, Airbus and the Regulators – have all issued communications according to their interests. In fact, the most detailed information about the accident has come from Airbus sources and not from Qantas or from Rolls Royce. But that is coincidental, since clearly Airbus is greatly concerned that the aircraft not be “unfairly” blamed.  Other manufacturers of parts for the Trent 900 have also been quick to point out that “they are not at fault”. Yesterday SKF and Volvo Aero who are both sub-suppliers to Rolls Royce Trent 900 engines rushed to point out that the components they supply were not involved.

But of course the relationship between the airlines and the manufacturers is a symbiotic one. Business Week goes on:

Qantas spokesman Tom Woodward said Qantas has complied with all safety orders. Rolls-Royce Group PLC said in an update to investors Friday that the Qantas engine incident last week was due to failure in a specific component that caused an engine fire and “the release of the intermediate pressure turbine disc.” The company will be replacing the relevant part “according to an agreed program” as inspections on the engine continue in association with aviation regulators, it said. The company did not provide details. The disc, a plate that holds the turbine blades that move air through the motor, broke apart in last week’s mishap. Lufthansa spokesman Thomas Jachnow said the German airline has been told “that Rolls-Royce will gradually replace a modular part of the engine on all Trent 900 engines.” He added that the “exact parts to be replaced haven’t been finalized yet.”

Airbus Chief Operating Officer John Leahy told reporters in Sydney that new versions of the Trent 900 engine that powers the Airbus A380 superjumbo will not suffer from the oil leaks that appear to have caused the fire on the Qantas flight. He said Rolls-Royce was equipping Trent 900s with software that would shut down a motor with leaking oil before it was put at risk of disintegration. Airbus said it planned to take newer versions of the Trent engine off its A380 production line and ship them to Qantas so that the airline could change the engines on some of its superjumbos.

“We think the engines on the production line will be fine,” The Age newspaper of Melbourne, Australia, quoted Leahy as saying. “The new engines should not have that issue … in terms of this one part that seems to have had a problem with leaking oil.”

The Herald Sun of Melbourne reported that Leahy said Rolls-Royce had made changes to some versions of engine to prevent such problems before the Nov. 4 mishap, but Airbus spokesman Justin Dubon denied the report. He said Leahy was referring to changes to the engines being made in light of the mishap.

Leahy, when asked whether he was suggesting that Rolls-Royce knew about problems with the engines before the Qantas incident, said, “Absolutely not,” according to Dubon. Dubon would not comment on whether changes had been made before the Qantas engine disintegrated, or whether the software Leahy described would be installed on engines already in service, referring those questions to Rolls-Royce. Rolls-Royce and the EASA declined repeated requests to comment about Leahy’s remarks.

A mechanic who works for an airline that uses the engine told The Associated Press, however, that Rolls-Royce made modifications to the oil lubrication system on Trent 900s delivered starting in the second half of 2009. The mechanic spoke on condition of anonymity because he was not permitted to speak to the media. The Qantas flight whose engine blew apart came into service in 2007.

Before last week’s disintegration there were four malfunctions involving Trent 900 engines dating to 2008, three of which centered on the turbines or oil system. All the planes landed safely.

Two of the malfunctions led to EASA warnings, including the directive issued in January and revised in August.

There are three turbines in the Trent 900 engine. The EASA order said wear had been found on parts in the intermediate turbine that could cause an oil leak. The order warned that oil leaking from the intermediate turbine could cause a fire under the adjacent lower turbine, causing the disc in that turbine to fail. Instead, there was an oil fire in the Qantas plane, but it was the intermediate turbine disc that failed. The two turbines are just a few inches apart, said Eastlake, the former aerospace engineering professor.

London-based Rolls-Royce said in an update to investors Friday that the incident will cause full year profit growth “to be slightly lower than previously guided,” but it also said that the company’s other operations will help to offset any losses.

Shares in the company rose after the update — a signal that investors are happy to see a definitive statement after days of silence from the world’s second-biggest engine maker behind General Electric.

There is clearly a need for looking again at the role of Regulators and how they create the balance between “public concern” and the interests of the industry they regulate. This is not unlike the balance in the financial world that regulators and auditors have spectacularly failed to achieve in recent years. This failure has been perhaps the primary cause of the financial crisis.

I cannot help thinking also that when the number of players is limited (as with aircraft suppliers or engine manufacturers) that there is a point beyond which competitive pressure can become counter-productive.


Emergency Airworthiness Directive issued for Trent 900

November 11, 2010

The European Aviation Safety Agency have released Emergency Airworthiness Directive (EAD) 2010-0236-E requiring operators of Trent 900 engines to perform inspections of their engines.

The Directive is applicable to the following engine variants: RB211 Trent 900 series engines, variants RB211 Trent 970-84, RB211Trent 970B-84, RB211 Trent 972-84, RB211 Trent 972B-84, RB211 Trent977-84, RB211 Trent 977B-84 and RB211 Trent 980-84, all serialnumbers.These engines are known to be installed on, but not limited to, AirbusA380 series aeroplanes.

Reason: An uncontained engine failure has recently occurred on a Rolls-RoyceTrent 900 involving release of high energy debris and leading to damage to the aeroplane.Analysis of the preliminary elements from the incident investigation showsthat an oil fire in the HP/IP structure cavity may have caused the failure ofthe Intermediate Pressure Turbine (IPT) Disc.This condition, if not detected, could ultimately result in uncontained engine failure potentially leading to damage to the aeroplane and hazardsto persons or property on the ground.For the reasons described above and pending conclusion of the incidentinvestigation, this AD requires repetitive inspections of the Low PressureTurbine (LPT) stage 1 blades and case drain, HP/IP structure air buffercavity and oil service tubes in order to detect any abnormal oil leakage,and if any discrepancy is found, to prohibit further engine operation.The requirements of this AD are considered as interim action. If, as a result of the on-going incident investigation, a terminating action is later identified, further mandatory actions might be considered.

Required as indicated, unless accomplished previously:

(1) Within the compliance times indicated in Table 1 of this AD, accomplish the following actions in accordance with Rolls-RoyceNon Modification Service Bulletin (NMSB) 72-AG590, Par 3. Accomplishment Instructions, 3.A or 3.B as applicable to the engine configuration:

(1.1) Carry out an extended ground idle run.

(1.2) Inspect the Low Pressure Turbine (LPT) stage 1 blades andcase drain.(1.3) Inspect the HP/IP structure air buffer cavity and oil service tubes.

(2) If any discrepancy is found during the inspections required by paragraph (1) of this AD, any further engine operation is prohibited. Within one day after the accomplishment of the inspection, report the findings to Rolls-Royce.

(3) Inspections accomplished in accordance with the content of NMSB72-AG590 before the effective date of this AD, are acceptable to comply with the initial inspections required by this AD.

(4) After the effective date of this AD, do not operate an engine on an aeroplane unless it has been inspected in accordance with the requirements of this AD.

The Aviation Herald points out that:

An oil fire possibly similiar to the Qantas Trent 972 led to an uncontained engine failure of a Trent 772 engine on Edelweiss’ Airbus A330-200 registration HB-IQZ near Miami, see Final Report: Edelweiss A330 at Miami on Oct 5th 2003, uncontained engine failure during departure. In their safety recommendations released in December 2006 following the conclusion of the investigation the NTSB wrote:

“Disassembly of the No. 1 engine revealed evidence of heat damage and distress in the HP/IP turbine bearing chamber consistent with the presence of an oil fire. Microstructure examination of the fracture surfaces on the IP turbine disk drive arm revealed damage consistent with a localized fire that caused the drive arm to eventually fail and separate, allowing the IP turbine disk to overspeed. The overspeed condition resulted in the liberation of all IP turbine disk blades through the IP turbine case, with some blades striking the airplane. Because thermal damage within the HP/IP turbine bearing chamber and associated hardware prevented identifying the exact cause of the fire based solely on the physical evidence from the No. 1 engine, the No. 2 engine was examined to help establish possible causes or contributors to the bearing chamber fire in the No. 1 engine.

A borescope inspection of the No. 2 engine revealed that the HP/IP turbine bearing chamber internal vent tube was obstructed with a black substance. An airflow check of the vent tube revealed that the air passage was not completely blocked. A nondestructive three-dimensional neutron tomography analysis revealed that the substance was not solid and was characterized by nodules of carbon deposits (also known as coke) with areas of voids. Although coke formations within oil tubes are not uncommon, the morphology, amount, and location of the carbon deposits found in the vent tube of the No. 2 engine were unusual and inconsistent with coke formation seen on other Trent engines or from other service experiences.”

The NTSB had concluded in April 2006 the probable cause of the Trent 772’s failure was:
“the coking (carbon build-up) in a vent tube which led to a fire and the subsequent liberation of the IP turbine blades. Contributing to the cause of the uncontained engine failure was the absence of measures to adequately monitor the in-service performance of a new engine/oil combination.”


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