GEnx "Bleedless" (B787) & GEnx "Bleed-Air" (B747-8)

The US Federal Aviation Administration is requiring General Electric to modify its GEnx-series engines by end-2012 to prevent fuel vapour leaks, in order to comply with a 1973 environmental regulation.
The ruling, published 25 July on the Federal Register, would affect all Boeing 787s powered by GEnx-1B engines and 747-8s, which are exclusively powered by the -2B model.
The leaks must be eliminated from all new-build GEnx engines by 31 December 2012 and in-service engines will require retrofit by 31 December 2014 in order to comply with the ruling.
According to the FAA, about .16l (5.5oz) of fuel from the GEnx is being released "intermittently under certain conditions" and is "vapourised on contact with hot surfaces inside the engine, resulting in the visible fuel vapours that have been observed when they emit from either the inlet or exit plane of the engine".
The 1973 rule, which the FAA called "short-sighted", prohibited a then common practice of dumping up to 3.8l (1gal) of raw fuel after engine shutdown, but the prohibition specifically sited "elimination of intentional discharge" prescribing specific intent of the operator.
While the FAA determined "no safety and minimal environmental effects are evident" after consultation with the Environmental Protection Agency, it said it remains "concerned about compliance with the intent of the current regulation" to prevent the intentional discharge of fuel.
Even though the rule does allow "normal fuel seepage from shaft seals, joints, and fittings", the GEnx fuel discharge is from none of the three allowed sources, thus creating a ambiguous interpretation and application of the regulation and as a result has prompted the requirement to modify the GEnx engines.
Boeing's 747-8 freighter is set to enter service before the end of September, with the passenger model to be delivered to a completion centre for outfitting in VIP configuration by the end of the year. Boeing has not identified a launch customer or timeline for the GEnx-1B's certification on the 787.

Furthermore, the fuel efficiency of the General Electric (GE) GEnx-2B engines is likely to be improved over time as the Ohio-based engine-maker mulls to feature the performance improvement package (PIP) 1 and PIP 2 going to be retrofitted on early batches of GEnx-powered Boeing 787 Dreamliner onto its bigger sibling.

“During our testing, we noticed we needed to improve our SFC, and GE has plans in place to ensure we meet the SFC targets on both engine lines [the GEnx-1B on the 787 and GEnx-2B on the 747-8] through the PIP (performance improvement package) programmes,” General Electric Aircraft Engines (GEAE) spokeswoman Deborah Case acknowledged.

“GE Aviation is looking into a PIP programme for the GEnx-2B (which would be PIP 1 on the -2B), but it has not been finalised. The -1B PIP 1 provides a 1.4% improvement in SFC than the original configuration. PIP 2 will bring an additional 1.5% improvement in SFC,” Case conceded.

The PIP 1 and PIP 2 would deliver a combined 2.9% of reduction in the GEnx-1B engine’s specific fuel consumption (SFC) and bring the -1B engine, widely believed to have missed its original SFC target by 2%-3%, in line or slightly better than the SFC target originally envisioned.

“For PIP 1, we are nearing the end of ground testing and working on the FAA certification. GE has conducted flight tests on the engine and the results have been very position,” Case asserted.

“GE did ship engines in late May for flight testing. We anticipate the PIP 1 entering service early next year. PIP 2 on the GEnx-1B engine began testing in December 2010. We anticipate engine certification in June 2012 and entry into service in late 2012 or early 2013,” Case clarified.

The PIP1 engine leverages a set of design changes made to the GEnx-2B developed for the 747-8, and has better fuel burn performance than the initial 787 engine standard. Just how much better this proves to be at the aircraft level will be decided when the PIP1-powered 787-8 test aircraft conducts key nautical air mi. (NAMS) fuel burn check flights. The current plan is for these to take place in “late August-early September,” says Fitzgerald.

GE originally intended to certify PIP1 at 75,000 lb thrust, but is splitting the effort into two phases following a test incident in May which resulted in an engine stall at high power during ground tests. This occurred toward the final stages of an FAA block test when the engine was operating at more than 30% above ‘red line’ temperatures.

The event led to the decision to certify the baseline PIP1 at 70,000 lb thrust and to redesign the high pressure turbine nozzle. This will be re-run through a new block test in November-December, he adds. Pending a successful evaluation, the revised variant will then be incorporated into the PIP1 and the certification will be amended to enable operation at up to 75,000 lb thrust. The target is to certify to the higher power level in February 2012, says Fitzgerald.

Beyond this GE is developing a second improvement package (PIP2) aimed at fuel burn performance within 1% of the original specification, yet with an additional 3,000lb thrust capability for the needs of the stretched 787-9. The second PIP2 engine is due to begin ground tests at GE’s Ohio site next week, and is targeted for Part 33 engine certification in mid-2012.

GE is “also in the process of putting together an offering to upgrade Block 4 engines to PIP2 standard,” Fitzgerald says. A further set of more than 30 Block 4 engines already built or in final assembly will meanwhile be provided to a “lease pool” of spare engines.

Overall, GE currently has around 60% of the 787 market in terms of unit sales with over 830 GEnx-1B engines sold. Fitzgerald says the PIP1 and PIP2 upgrades are aimed at maintaining the engine makers’ claimed fuel burn advantage over the competing Rolls-Royce Trent 1000.

It’s early days but, so far according to program insiders, initial indications from the flight test performance data on the 787 is giving GE encouragement that the GEnx-1B performance improvement package (PIP1) is working to plan. The first aircraft to be equipped with the upgraded engine, ZA005, is continuing starting tests having made its first flight in late September. The aircraft was selected for certification flight tests of the PIP1 as it is configured with a full instrumentation suite. After a series of initial low-altitude test start conditions ZA005 is expected to depart within the next few days for La Paz, Bolivia for high-altitude start tests.
Certification flight tests of the Block 4 standard GEnx-1B-powered 787 is meanwhile complete. The test aircraft, ZA006, is conducting ETOPS and Functional and Reliability (F&R) tests, and is scheduled to fly to Barbados in the Caribbean sometime around Oct 10 to conduct tests in high humidity conditions.
For the Rolls-Royce ETOPS/F&R phase Boeing used the island of Guam for these tests, however as a result of logistics issues encountered there the decision was made to relocate these to the Caribbean.


PIP1 standard engines are powering ZA005 (Boeing)

Boeing delivery order schedules for the first PIP1-powered 787 meanwhile continue to fluctuate according to sources. As of mid-August the first PIP1 aircraft was expected to be delivered to JAL in late November with a rating of 70,000lb. Now, however, the latest betting is on Air India receiving the first by the end of the year - but there is every expectation this could change again.
GE originally planned to certify PIP1 for entry-into-service at 75,000 lb thrust, but an unexpected stall during the final cycle of block testing at over 35% above maximum exhaust gas temperature, forced a redesign of the high pressure (HP) turbine nozzle. The revised nozzle is set for block tests later this year and will be certificated to 75,000lb thrust as part of an amended Part 33 ticket in February 2012.
PIP1 is focused on improvements to the LP turbine, while the second PIP will upgrade the HP and LP compressor as well as the turbine. PIP 2 is designed to ensure an improved fuel burn to within 1% of the specification at the higher thrust levels of 78,000lb required by the stretched 787-9. The PIP2 package is targeted at engine certification in mid-2012.

The US Federal Aviation Administration (FAA) has granted General Electric 330min extended operations (ETOPS) approval for its GEnx-1B powerplant, in another step toward the powerplant's final certification for long over water flights aboard the Boeing 787.

The engine-maker completed the required 3,000 cycle ETOPS ground endurance validation in April and will enable 787s to fly 330min from a primary or alternate airport, providing optimal routes for long-range flying.

Final FAA certification of the GE engine-airframe combination was expected in late 2011, but is expected to slip into early 2012, following the late readiness of a production 787, Airplane 35 for Air India, to satisfy final regulatory requirements for systems functionality and reliability and ETOPS validation.

First delivery to GEnx-1B launch customer Japan Airlines is planned for early 2012, said Boeing Commercial Airplane CEO Jim Albaugh on 30 November.

Despite the 330min certification of the GEnx-1B and Rolls-Royce Trent 1000, the aircraft remains limited to 180min ETOPS until a software fix for the flight deck's fuel quantity indication is implemented in 2012.

I do not know about the RR, but on the GE side the engine/nacelle issues would result in beyond contract wear and tear. Actually, with the fuel burn misses that have been discussed, full thrust takeoffs would be costly and have more risk than should be taken at this point. The turbine inlet temperatures for a 30C hot day takeoff would be brutal.

Air India's 787 fleet will initially be powered by GEnx-1B67 engines rated at 70,000lbs of thrust before being de-rated to 67,000lbs after Boeing completes the certification of the reduced thrust setting, said the filing.

Flight tests of the higher-thrust General Electric engine, standard for the stretched Boeing 787-9, indicate performance is on track to meet targeted fuel burn improvements for service entry on 787-8s early in 2013 and -9s in 2014.

The engine is the second of GE’s two-stage GEnx-1B performance improvement package (PIP) upgrades and has made more than 20 flights on the company’s 747 flying testbed since the first sortie on Feb. 3. “That’s about 80% complete,” says GEnx programs General Manager Chuck Nugent, who adds initial results show performance is on target. Testing conducted toward the end of March included high-altitude performance evaluations at Colorado Springs, Colo.

PIP II includes changes to the fan and high-pressure compressor and is aimed at recovering at least a further 1.1% fuel burn. The upgrade also raises available thrust to 78,000 lb. Although GE says Boeing has not specifically asked for this higher rating, the engine maker believes 787-9 weights may grow to take advantage of the elevated rating in due course.

Boeing is expected to begin test flying PIP II on a 787-8 in “the summer of 2012” with flight tests on the 787-9 in 2013. The upgrade forms part of GE’s drive to bring the aircraft back to Boeing’s original fuel burn specification. The first element, the PIP I upgrade, was delivered on the first aircraft for Japan Airlines on March 26 and will enter commercial service when the carrier begins flights from Tokyo to Boston on April 22. The first PIP I aircraft was originally expected to be delivered to JAL in late November 2011, but production disruption at Boeing, bad weather and a failed lightning test in December pushed deliveries into this year.

PIP I, which improved engine specific fuel consumption about 1.6%, was certified using ZA005, one of the original 787 test aircraft. Still powered by PIP I engines, this aircraft performed crosswind testing in Iceland in early February as part of the final phase of certification tests.

An aircraft destined for Air India meanwhile was used to complete type certification by conducting a small number of repeat extended-range, twin-engine operations flights and 150 hours of functionality and reliability flying that was required by the FAA.

Boeing is working to complete the full analysis of nautical air miles (NAMS) fuel testing that was flown with the PIP I-powered aircraft in the next few weeks, but initial indications are that the NAMS results “exceeded expectations,” adds former GEnx Project Manager Tom Brisken. “We’re still in the final analysis with the Boeing team, but we are quite pleased,” he adds.

GE says initial performance data show its GEnx-1B engine has a 2% fuel burn advantage over the competing Rolls-Royce Trent 1000, not counting an additional 1% benefit from expected performance retention in terms of sustained exhaust gas temperature margin. The first GEnx-1Bs are in service with JAL, while 787 launch operator ANA uses aircraft powered by the Trent 1000.

GE’s claimed advantage over the Trent 1000 comes as it monitors the early performance figures from the first eight engines in service with JAL. Meanwhile, the FAA certificated the 75,000-lb.-thrust variant of its GEnx-1B PIP1 (product improvement package) upgrade on June 14. The engines already in service with JAL are also built to the PIP standard certificated in August 2011, but are rated at a lower thrust level.

PIP1 was designed to improve fuel burn by around 1.6% compared to the baseline GEnx-1B, although the latest in-service data suggest this may have been conservative. PIP1 included a new low-pressure turbine, a revised control schedule and hot section upgrades. GE is currently developing a second PIP package which is aimed at an additional 1.1%.

The upgrade builds on PIP1 and adds 0.5-in. to the fan diameter, optimized outlet guide vanes, improved high-pressure compressor aerodynamics, upgrades to the low-pressure compressor and durability enhancements to the combustor and high-pressure turbine. The second PIP will be certificated in the fourth quarter of this year and will enable thrust growth to 78,000 lb.

Admin a écrit:Ben ils ne sont pas à la rue

2% de mieux avec le PIP1 puisqu'il est en service est-ce grave
Et pour la rétention, ça n'engage que ceux qui le dise non ?