NTSB. FAA. Rapports et AD

Two of the three main Trent 900 operators, Singapore Airlines (SIA) and Lufthansa, turned up no findings on the engines of their Airbus A380 fleets, after the European Aviation Safety Agency (EASA) issued and airworthiness directive (AD) for engine checks last week.

The moves were caused by a fault in one engine on a SIA A380 flight from Singapore to Hongkong in July. At the time, pilots noticed a high intermediate-pressure vibration fault and fluctuating engine parameters, including low-pressure faults. They decided to throttle back the engine and turn back to Singapore. There were no issues with the other engines.

Both SIA and Lufthansa, which operate two of the three largest Trent 900 A380s fleets, have completed checks on all of their aircraft. Singapore Airlines has 18 A380s in service, Lufthansa has 10. Qantas—operating 12 aircraft of the type—could not be reached for comment immediately on Friday.

According to EASA, the spherical seat between the oil transfer tube and the end cover of the low-pressure turbine bearing housing was missing, and the agency assumes that it simply has not been installed on the particular engine.

Because of the fault, the low-pressure system seized up. EASA said that the missing part caused the fracture of the oil tube and led to reduced oil flow and damage to the low-pressure and intermediate-pressure bearings. Rolls-Royce has indicated to EASA that other Trent 900 could potentially be affected, and the safety agency said the fault could lead to an uncontained engine failure.

The AD requires checks within as few as 20 engine cycles.

Of the A380 operators, Singapore Airlines, Lufthansa, Malaysia Airlines, China Southern and Qantas Airways are affected. Other airlines have equipped their A380s with Engine Alliance GP7200 engines.

The problems are unrelated to the November 2010 uncontained engine failure of Qantas Flight 32 in Singapore.

Vu ! Vu ? On ne saurait être plus clair ! Il est grand temps que les ignares et Agités des Forums d'ailleurs, et d'autres scribouillards du même tonneau, .. de mauvaise foi et bourrés de pârti-pris, cessent de faire les amalgames faux et trompeurs, ... voire, dans certais cas, .... mensongers !

At the time, the aircraft had to return to Singapore after engine debris caused severe damage mainly to the wing. The affected aircraft has only recently been repaired.

Au lieu de ressasser cela, il serait plus pertinent que les scribouillards s'occupent des problèmes du GEnx -1B !

US NTSB recommends anti-ground collision aids for large aircraft

The US National Transportation Safety Board (NTSB) has recommended the US FAA require large aircraft be equipped with an anti-ground collision aid.

NTSB recommends systems such as an onboard external-mounted camera to provide pilots a clear view of the aircraft’s wingtips while taxiing to ensure clearance from other aircraft, vehicles and obstacles.
According to the NTSB, on large aircraft—such as the Boeing 747, 757, 767 and 777; the Airbus A380; and the McDonnell Douglas MD-10 and MD-11—the pilot cannot see the wingtips from the cockpit “unless the pilot opens the cockpit window and extends his or her head out of the window, which is often impractical.”

The recommendation follows three recent ground collision accidents in which large aircraft collided with another aircraft while taxiing.

These included a May 30 incident in which the right wingtip of an EVA Air Boeing 747-400 struck the rudder and vertical stabilizer of an American Eagle Embraer 135; an incident in which the left winglet of a Delta Air Lines Boeing 767 struck the horizontal stabilizer of an Atlantic Southeast Airlines Bombardier CRJ900 ([Vous devez être inscrit et connecté pour voir ce lien]); and an incident in which the left wingtip of an Air France Airbus A380 struck the horizontal stabilizer and rudder of a Comair Bombardier CRJ701 ([Vous devez être inscrit et connecté pour voir ce lien]).

In a statement, NTSB said the anti-collision aids should be installed on newly manufactured and certificated airplanes and that existing large airplanes should be retrofitted with the equipment.
NTSB said it made the same recommendation to the European Aviation Safety Agency.

An Airlines for America spokesperson said the organization was studying the recommendations.

US aircraft safety investigators have called for grounding certain Boeing [Vous devez être inscrit et connecté pour voir ce lien] and 747-8s powered by General Electric engines until they are inspected for cracks and also revealed that a cracked fan midshaft was discovered on a third engine last month.

• comprendre ce que c'est un moteur / réacteur d'avion,
  
• réaliser que les problèmes sont bien chez GE et au sein de son GEnx (conception, "design", choix des matériaux zt "processes", ... exécution de la réalisation ; à examiner en profondeur).
  

The recommendations issued by the National Transportation Safety Board (NTSB) offer the clearest explanation yet for the rash of zero- or low-time GEnx engine failures since 28 July.

The NTSB letter sent to the Federal Aviation Administration also reveals that an analysis of the fan midshaft fractures do not point to metal fatigue as a likely cause. The fan midshaft connects the low pressure turbine to the fan and booster stages at the forward end of the engine.

Instead, the cracks in the critical engine component are "typical of environmentally assisted cracking of certain high strength alloys such as that used on the GEnx [fan midshaft]", the NTSB letter says.

The NTSB is continuing to investigate what is triggering the environmentally assisted cracking. According to GE, such metals crack as a result of galvanic corrosion caused by a moist environment with the presence of hydrogen.

A potential trigger of the galvanic corrision could have been revealed earlier this week. In a statement issued by GE on 11 September, the company said it has changed the coating process for the fan midshaft on the production line as a result of the engine failures.

GE says today that the new coating process changes the dry film applied to the midshaft, and replaces the lubricant used when a retaining nut is clamped to the midshaft.

The NTSB's letter to the FAA indicates all three engine failures discovered to date could be linked to the same cause.

The latest engine failure to be revealed actually was discovered during an ultrasound inspection on 13 August, but it was not disclosed to the public until now.

The ultrasound check on the engine, which was installed on a 787 that had not been flown, revealed an indication of a "similar" crack on the fan midshaft.

The first such incident occurred on 28 July. An engine on an Air India [Vous devez être inscrit et connecté pour voir ce lien] in Charleston, South Carolina, failed in low-speed taxi test. The crew was accelerating the aircraft through 40kt when the low-pressure speed rolled back on the No. 2 engine. The crew aborted the test and a visual inspection revealed the first stage of the low pressure turbine had shifted backward, colliding into trailing stages.

Six weeks later, a Boeing 747-8F operated by Air Bridge Cargo with about 1,200 flight hours and 240 cycles experienced a similar problem. As the aircraft accelerated through 50kt, the low-pressure turbine speed of the No. 1 engine dropped. The crew rejected the take-off and an inspection revealed "extensive damage" to the low pressure turbine, the NTSB letter says.

The NTSB highlighted the potential safety danger of repeated failures on low-time engines.

The board's letter highlighted the "possibility that multiple engines on the same airplane could experience a (fan midshaft) failure".

In the event of an extended twin-engine flight over water, for example, the aircraft would have to operate on only a single engine for up to 5.5h, the NTSB letter says.

In response, GE says in a statement that it has already recommended repetitive inspections to the FAA and is close to completing ultrasonic inspections of the fan midshaft for all GEnx engines in service.

Boeing adds that is working with GE to inspect nine 747-8Fs within a "few days" to complete ultrasound inspections on the operational GEnx fleet.

US aircraft safety investigators have called for grounding certain Boeing [Vous devez être inscrit et connecté pour voir ce lien] and 747-8s powered by General Electric engines until they are inspected for cracks and also revealed that a cracked fan midshaft was discovered on a third engine last month.

The recommendations issued by the National Transportation Safety Board (NTSB) offer the clearest explanation yet for the rash of zero- or low-time GEnx engine failures since 28 July. The NTSB letter sent to the Federal Aviation Administration also reveals that an analysis of the fan midshaft fractures do not (Sevrien : "does not...") point to metal fatigue as a likely cause. The fan midshaft connects the low pressure turbine to the fan and booster stages at the forward end of the engine.

Instead, the cracks in the critical engine component are "typical of environmentally assisted cracking of certain high strength alloys such as that used on the GEnx (fan midshaft)", the NTSB letter says. The NTSB is continuing to investigate what is triggering the environmentally assisted cracking.

According to GE, such metals crack as a result of galvanic corrosion caused by a moist environment with the presence of hydrogen.

A potential trigger of the galvanic corrosion could have been revealed earlier this week. In a statement issued by GE on 11 September, the company said it has changed the coating process for the fan midshaft on the production line as a result of the engine failures.

GE says today that the new coating process changes the dry film applied to the midshaft, and replaces the lubricant used when a retaining nut is clamped to the midshaft.

The NTSB's letter to the FAA indicates all three engine failures discovered to date could be linked to the same cause.

The latest engine failure to be revealed actually was discovered during an ultrasound inspection on 13 August, but it was not disclosed to the public until now.

The ultrasound check on the engine, which was installed on a 787 that had not been flown, revealed an indication of a "similar" crack on the fan midshaft.

The first such incident occurred on 28 July. An engine on an Air India [Vous devez être inscrit et connecté pour voir ce lien] in Charleston, South Carolina, failed in low-speed taxi test. The crew was accelerating the aircraft through 40kt when the low-pressure speed rolled back on the No. 2 engine. The crew aborted the test and a visual inspection revealed the first stage of the low pressure turbine had shifted backward, colliding into trailing stages.

Six weeks later, a Boeing 747-8F operated by Air Bridge Cargo with about 1,200 flight hours and 240 cycles experienced a similar problem. As the aircraft accelerated through 50kt, the low-pressure turbine speed of the No. 1 engine dropped. The crew rejected the take-off and an inspection revealed "extensive damage" to the low pressure turbine, the NTSB letter says.

The NTSB highlighted the potential safety danger of repeated failures on low-time engines. The board's letter highlighted the "possibility that multiple engines on the same airplane could experience a (fan midshaft) failure". In the event of an extended twin-engine flight over water, for example, the aircraft would have to operate on only a single engine for up to 5.5h, the NTSB letter says.

In response, GE says in a statement that it has already recommended repetitive inspections to the FAA and is close to completing ultrasonic inspections of the fan midshaft for all GEnx engines in service.

Boeing adds that is working with GE to inspect nine 747-8Fs within a "few days" to complete ultrasound inspections on the operational GEnx fleet.

The US Federal Aviation Administration said on Wednesday it would stop short of issuing an emergency directive on recently identified problems in General Electric engines on a pair of Boeing jet models, sticking instead to more routine safety notices.
An emergency directive could have meant temporary groundings of the GE-powered Boeing 787 and 747-8 jets, for instance, or other significant caps on fleet operations that now may be less likely.

The issue emerged July 28 when a GEnx engine on a Boeing 787 Dreamliner failed during a pre-flight taxi test at Charleston Airport in South Carolina, sparking a small fire by the runway. On September 11, a GEnx-powered Boeing 747-8 freighter was forced to abort a take-off from Shanghai after it lost thrust.

"The FAA will soon issue an airworthiness directive and will take appropriate action," the FAA said in a statement that dropped its previous reference to its preparing to release an emergency directive to deal with the matter.

"It is NOT an emergency AD," an FAA spokeswoman said in an email. AD is short for airworthiness directive, a notice to aircraft operators of a known safety defect.

GE had no immediate comment on the FAA's decision to forego an emergency directive.

Jim Proulx, a spokesman for Boeing, said the company could not comment nor speculate on any action the FAA might take in the matter.

The FAA is expected to issue its directive on Friday or next Monday.

Separately, Boeing said it plans to deliver the first 787 made in South Carolina next week, a jet equipped with GEnx engines, noting the engines have undergone special inspection.

"We have done the checks on all our GE engines," Jack Jones, Boeing vice president and general manager, said on Wednesday at an international trade conference near Charleston. "GE has done a great job of figuring out quickly what we have to do to ensure the integrity of the engine. We know that and we've implemented it."

Jones said the engine issue had not affected Boeing's schedule of delivering planes. "It obviously didn't stop deliveries. That is absolutely critical," he said.

Analysts said it now appears the FAA would call for repetitive, short-interval inspections of the GE engines, possibly because the root cause and a solution have been found.

"As long as the upcoming directive does not materially restrict the affected aircraft from flying their intended flight profiles, we think it safe to say that Boeing has dodged the bullet on this one," said Carter Leake, an aerospace analyst with BB&T Capital Markets.

Leake had said in a recent note to investors that "we would not be surprised if Air India opted not to close on aircraft due for immediate delivery this month" due to concerns about the GE engines.

GE has introduced a new coating process to affected parts of new engines, a company spokesman said.

"The change to different coatings, which has already been certified on other GE engines like the GE90, is FAA-approved for GEnx production," he said.

On Friday, the National Transportation Safety Board had issued two "urgent" safety recommendations to the FAA after it had found cracks or crack indications in a GEnx engine part called the fan midshaft.

The recommendations were, first, to issue an airworthiness directive to require, before further flight, the immediate ultrasonic inspection of the fan midshaft in all GEnx-1B and -2B engines that had not undergone inspection.

The second was to require repetitive inspections of the fan midshaft at a "sufficiently short interval" that would permit multiple inspections and detection of a crack before it could reach critical length.

The FAA, in its statement, said inspections already have been completed on all passenger planes, none of which are with US airlines. Atlas Cargo Airlines is the only operator with two US registered aircraft, it said.

"We understand both inspections were completed with no findings" of cracks, the statement added.

Hans Weber of TECOP International, a consultant on aerospace technology, said it appeared that the root cause of the fracture problem had been determined to the satisfaction of GE, Boeing and the FAA.

The intervals between repeat inspections is in the process of being determined by GE and the FAA, he said.

(Reuters)

SUMMARY: We are adopting a new airworthiness directive (AD) for General
Electric Company GEnx-1B54, GEnx-1B58, GEnx-1B64, GEnx-1B67, GEnx-1B70,
GEnx-1B54/P1, GEnx-1B58/P1, GEnx-1B64/P1, GEnx-1B67/P1, GEnx-1B70/P1,
GEnx-1B70/72/P1, GEnx-1B70/75/P1, GEnx-1B74/75/P1, GEnx-1B75/P1, GEnx-
2B67, and GEnx-2B67B turbofan engines. This AD requires initial and
repetitive ultrasonic inspections (UI) of certain part number (P/N) fan
mid shafts (FMS) for cracks. This AD was prompted by a report of an FMS
failure and a report of a crack found in another FMS. We are issuing
this AD to prevent failure of the FMS resulting in one or more engine
failure(s) and possible loss of the airplane.

DATES: This AD is effective September 21, 2012.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in the AD as of September 21,
2012.
We must receive comments on this AD by October 22, 2012.

ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to [Vous devez être inscrit et connecté pour voir ce lien]. Follow the instructions for submitting comments.
Fax: 202-493-2251.
Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE., Washington, DC 20590.
Hand Delivery: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE., Washington, DC 20590, between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays.
For service information identified in this AD, contact General
Electric Company, GE-Aviation, Room 285, 1 Neumann Way, Cincinnati, OH
45215, phone: (513) 552-3272; email: [Vous devez être inscrit et connecté pour voir ce lien]. You may view this
service information at the FAA, Engine & Propeller Directorate, 12 New
England Executive Park, Burlington, MA. For information on the
availability of this material at the FAA, call 781-238-7125.

Examining the AD Docket

You may examine the AD docket on the Internet at [Vous devez être inscrit et connecté pour voir ce lien]; or in person at the Docket Management Facility
between 9 a.m. and 5 p.m., Monday through Friday, except Federal
holidays. The AD docket contains this AD, the regulatory evaluation,
any comments received, and other information. The street address for
the Docket Office (phone: 800-647-5527) is in the ADDRESSES section.
Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: James Gray, Aerospace Engineer, Engine
Certification Office, FAA, Engine & Propeller Directorate, 12 New
England Executive Park, Burlington, MA 01803; phone: 781-238-7742; fax:
781-238-7199; email: [Vous devez être inscrit et connecté pour voir ce lien].

SUPPLEMENTARY INFORMATION:

Discussion

On July 28, 2012, we received a report of a GEnx-1B engine failure
installed on a Boeing 787 (B787) airplane. Boeing was conducting
routine ground testing of the B787, before aircraft delivery. During a
taxi test, one engine's FMS fractured just aft of the coupling nut. The
low-pressure turbine (LPT) rotor shifted axially backwards, resulting
in LPT blade and vane clashing. The LPT case contained the failure and
debris was released out the tailpipe. There was no engine overspeed as
the LPT rotor remained coupled to the fan rotor at the FMS spline. On
August 14, 2012, we received a second report concerning the GEnx
engine, this time about an FMS, installed in a GEnx-1B engine, that was
found cracked during an on-wing UI. This condition, if not corrected,
could result in failure of the FMS resulting in one or more engine
failure(s) and possible loss of the airplane.

Relevant Service Information

We reviewed GE Service Bulletin (SB) No. GEnx-1B S/B 72-0107,
Revision 2, dated September 14, 2012, and SB No. GEnx-2B S/B 72-0091,
Revision 1, dated September 14, 2012. The SBs describe procedures for
performing UI inspections of FMS P/N 2331M20G02, P/N 2332M81G01, and P/
N 2332M33G01.

FAA's Determination

We are issuing this AD because we evaluated all the relevant
information and determined the unsafe condition described previously is
likely to exist or develop in other products of the same type design.

FAA's Justification and Determination of the Effective Date

An unsafe condition exists that requires the immediate adoption of
this AD. The FAA has found that the risk to the flying public justifies
waiving notice and comment prior to adoption of this rule based on the
reported engine failure, the crack find, and that the root

[[Page 58472]]

cause is still somewhat unknown. We therefore determined that a
repetitive inspection interval needed to be established. The repetitive
inspection interval is less than the time it would take to process a
proposed AD. Therefore, we find that notice and opportunity for prior
public comment are impracticable and that good cause exists for making
this amendment effective in less than 30 days.

Comments invited

This AD is a final rule that involves requirements affecting flight
safety and was not preceded by notice and an opportunity for public
comment. However, we invite you to send any written data, views, or
arguments about this AD. Send your comments to an address listed under
the ADDRESSES section. Include the docket number FAA-2012-1017 and
Directorate Identifier 2012-NE-30-AD at the beginning of your comments.
We specifically invite comments on the overall regulatory, economic,
environmental, and energy aspects of this AD. We will consider all
comments received by the closing date and may amend this AD because of
those comments.
We will post all comments we receive, without change, to [Vous devez être inscrit et connecté pour voir ce lien], including any personal information you provide. We will also post a report summarizing each substantive verbal contact we
receive about this AD.

Costs of Compliance

We estimate that this AD will affect 11 GE GEnx turbofan engines
installed on airplanes of U.S. registry. We also estimate that it will
take about 9 work-hours per engine to perform the UI of the FMS, and
that the average labor rate is $85 per work-hour. The estimated cost of
one set of inspection tooling is $105,000. Based on these figures, we
estimate the total cost of this AD to U.S. operators to be $113,415.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. ``Subtitle VII: Aviation Programs''
describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701: ``General
requirements.'' Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on products identified in this
rulemaking action.

Regulatory Findings

This AD will not have federalism implications under Executive Order
13132. This AD will not have a substantial direct effect on the States,
on the relationship between the national government and the States, or
on the distribution of power and responsibilities among the various
levels of government.
For the reasons discussed above, I certify that this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Is not a ``significant rule'' under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979),
(3) Will not affect intrastate aviation in Alaska, and
(4) Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

Adoption of the Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec. 39.13 [Amended]

0
2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive (AD):

2012-19-08 General Electric Company: Amendment 39-17203; Docket No.
FAA-2012-1017; Directorate Identifier 2012-NE-30-AD.

(a) Effective Date

This AD is effective September 21, 2012.

(b) Affected ADs

None.

(c) Applicability

This AD applies to:
(1) General Electric Company (GE) GEnx-1B54, GEnx-1B58, GEnx-
1B64, GEnx-1B67, GEnx-1B70, GEnx-1B54/P1, GEnx-1B58/P1, GEnx-1B64/
P1, GEnx-1B67/P1, GEnx-1B70/P1, GEnx-1B70/72/P1, GEnx-1B70/75/P1,
GEnx-1B74/75/P1, and GEnx-1B75/P1 turbofan engines with fan mid
shaft (FMS) part number (P/N) 2331M20G02 or P/N 2332M81G01,
installed; and
(2) GE GEnx-2B67 and GEnx-2B67B turbofan engines with FMS P/N
2332M33G01, installed.

(d) Unsafe Condition

This AD was prompted by a report of an FMS failure and a report
of a crack found in another FMS. We are issuing this AD to prevent
failure of the FMS resulting in one or more engine failure(s) and
possible loss of the airplane.

(e) Compliance

Comply with this AD within the compliance times specified,
unless already done.

(f) Ultrasonic Inspections (UIs)

(1) Perform an initial UI for cracks in the FMS before further
flight.
(2) Thereafter, perform repetitive UIs for cracks in the FMS
within every 90 days since-last-inspection.
(3) Remove any cracked FMS from service before further flight.
(4) For engines listed in paragraph (c)(1) of this AD, use
paragraphs 3.A and 3.B.(1) through 3.B.(9) of the Accomplishment
Instructions of GE Service Bulletin (SB) No. GEnx-1B S/B 72-0107,
Revision 2, dated September 14, 2012, to do the inspections.
(5) For engines listed in paragraph (c)(2) of this AD, use
paragraphs 3.A and 3.B.(1) through 3.B.(9) of the Accomplishment
Instructions of GEnx-2B S/B 72-0091, Revision 1, dated September 14,
2012, to do the inspections.

(g) Alternative Methods of Compliance (AMOCs)

The Manager, Engine Certification Office, FAA, may approve AMOCs
to this AD. Use the procedures found in 14 CFR 39.19 to make your
request.

(h) Credit for Actions Accomplished in Accordance With Previous Service
Information

(1) For engines listed in paragraph (c)(1) of this AD, if you
performed the initial inspection before the effective date of this
AD using GE SB No. GEnx-1B S/B 72-0107, dated August 17, 2012, or
Revision 1, dated August 24, 2012, you met the requirement of
paragraph (f)(1) of this AD.
(2) For engines listed in paragraph (c)(2) of this AD, if you
performed the initial inspection before the effective date of this
AD using GE SB No. GEnx-2B S/B 72-0091, dated August 22, 2012, you
met the requirement of paragraph (f)(1) of this AD.
(3) For engines listed in paragraphs (c)(1) or (c)(2) of this
AD, if an initial inspection was performed before the effective date
of this AD using GE Field Engineering Instruction (FEI) GEnx-1B No.
2012-014 Fan Mid Shaft Inspection, or FEI GEnx-2B No. 2012-017 Fan
Mid Shaft Inspection, you met the requirement of paragraph (f)(1) of
this AD.

[[Page 58473]]

(i) Related Information

For more information about this AD, contact James Gray,
Aerospace Engineer, Engine Certification Office, FAA, Engine &
Propeller Directorate, 12 New England Executive Park, Burlington, MA
01803; phone: 781-238-7742; fax: 781-238-7199; email:
[Vous devez être inscrit et connecté pour voir ce lien].

(j) Material Incorporated by Reference

(1) The Director of the Federal Register approved the
incorporation by reference (IBR) of the service information listed
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) You must use this service information as applicable to do
the actions required by this AD, unless the AD specifies otherwise.
(i) General Electric Company Service Bulletin No. GEnx-1B S/B
72-0107, Revision 2, dated September 14, 2012.
(ii) General Electric Company Service Bulletin No. GEnx-2B S/B
72-0091, Revision 1, dated September 14, 2012.
(3) For General Electric Company service information identified
in this AD, contact General Electric Company, GE-Aviation, Room 285,
1 Neumann Way, Cincinnati, OH 45215, phone: (513) 552-3272; email:
[Vous devez être inscrit et connecté pour voir ce lien].
(4) You may view this service information at the FAA, Engine &
Propeller Directorate, 12 New England Executive Park, Burlington,
MA. For information on the availability of this material at the FAA,
call 781-238-7125.
(5) You may view this service information at the National
Archives and Records Administration (NARA). For information on the
availability of this material at NARA, call 202-741-6030, or go to:
[Vous devez être inscrit et connecté pour voir ce lien].

Issued in Burlington, Massachusetts, on September 17, 2012.
Diane M. Cook,
Acting Manager, Engine & Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 2012-23443 Filed 9-20-12; 8 am]
BILLING CODE 4910-13-P

Here's [Vous devez être inscrit et connecté pour voir ce lien] ordering immediate inspections of GE GEnx fan mid-shafts (FMS). No big news, as all operators have performed the checks per a GE service bulletin issued Sept. 14, [Vous devez être inscrit et connecté pour voir ce lien] over on the pay-to-read part of Planet AvWeek.

In fact, the directive is notable for what's not in it--namely, any mention of [Vous devez être inscrit et connecté pour voir ce lien] on an Air Bridge 747-8F during a takeoff run in Shanghai that [Vous devez être inscrit et connecté pour voir ce lien] three days later. The FAA directive cites [Vous devez être inscrit et connecté pour voir ce lien] and, during inspections prompted by that incident, an August 13 discovery of a cracked GEnx fan mid-shaft found on a 787 that hadn't flown yet.

FAA's non-reference of NTSB's recommendation is no surprise--the agency's official stance is that many factors go into the issuance of an AD. Besides, FAA isn't all that big on acknowledging when its movement has been helped along by a nudge from the safety board.

NTSB, on the other hand, has no such reservations. In fact, [Vous devez être inscrit et connecté pour voir ce lien] on the GEnx AD came from the board itself. Lauded the board:

The NTSB applauds the Federal Aviation Administration's (FAA) action calling for immediate initial and recurring inspections of the fan midshaft installed in General Electric (GE) GEnx-1B and -2B engines that power Boeing 787 and 747-8 airplanes. Although the NTSB will be evaluating the details of these actions to determine their responsiveness to its September 14th urgent safety recommendations, the NTSB is encouraged by this action.

SEVRIEN a écrit:

Hans Weber of TECOP International, a consultant on aerospace technology, said it appeared that the root cause of the fracture problem had been determined to the satisfaction of GE, Boeing and the FAA......


(Reuters)

Oui. "Wait & see" !

Réactions à ce stade ?

vonrichthoffen a écrit:Bonsoir.

Plus sérieusement (j'espère), quelques réflexions.

Les phénomènes d'électrolyse sont parfois imprévisibles dans leur intensité, même s'ils peuvent l'être dans leur principe au stade R&D.

Une pièce soumise à des flux d'air ou de gaz de combustion dans ces circonstances, où l'on retrouve vitesse d'écoulement, pression et température, a toutes les chances d'être soumise à de fortes charges électrostatiques, la présence d'Hydrogène créant des conditions électrolytiques.

D'où vient cet Hydrogène ?

La thèse du surplus de graisse au montage peut tenir la route, il ne doit pas en falloir beaucoup mais les fissures devraient rester locales, ce qui ne les empêcherait pas d'être destructrices.

A priori, l'humidité en tant qu'éventuelle source d'Hydrogène pourrait avoir des origines multiples: process du coating, environnement du process, - du matériau sui generis ou même de l'air admis par le moteur (il peut y avoir les conditions d'un cracking des molécules d'eau dans une chambre des combustion).

Ce que l'on peut se demander, vu la brutalité du phénomène et sa répétition, c'est pourquoi ces problèmes ne se sont pas révélés sur les prototypes.

Le fix proposé est raisonnable, en ce sens qu'il revient à des solutions éprouvées, même si l'on en connait les limites dans le cas des GE-90.
Il faut rendre ces moteurs airworthy dans la limite du raisonnable, n'est-ce pas ?

Qui va accorder la moindre crédibilité à GE sur les toutes nouvelles générations de moteur, en attendant que la vraie "root cause" des problèmes de 'mid-shaft cracking' des GEnx -1B & -2B soit découverte et les véritables "root solutions" soient développées, testées et implémentées ? Qu'on ne se leurre pas ! La "root cause" est encore en train d'être recherchée. C'est une affaire bien plus profonde -- bien plus profonde et compliquée -- que celle du RR Trent 900, ou celle du "Gearbox" de Hamilton Sundstrand sur le RR Trent 1000 ! Et tous les professionnels des moteurs d'avions -- tous les vrais -- le savent ! Et ils savent que le temps déjà passé sur ce dossier est tout simplement insuffisant pour avoir permis de trouver la "root cause" ou la combinaison des "root causes" dans cette affaire ! "

Ingénieur-Moteurs a écrit:Il ne s'agit pas de "metal fatigue". On ne peut, donc, pas soigner le problème en remplaçant les pièces plus souvent. Le problème est le "environmentally generated cracking". Les fissures se propagent et s'étendent à des rythmes différenciés, et imprévisibles. Le 'fix' est valable, .... mais aura des limites. On ne peut ni prévoir ni contrôler la naissance et / ou le développement de la fissuration. Il est difficile de gérer les inspections, et de tirer les conclusions appropriées de ces inspections. Cela ne va pas être facile pour Boeing, pour GE, pour les Cies. aériennes, ou pour les Autorités.

Boeing 787 Fuel Leaks Spur FAA to Require Jet Inspections

[Vous devez être inscrit et connecté pour voir ce lien]’s new 787 Dreamliners must be inspected after fuel leaks on two planes were traced to manufacturing errors, the U.S. [Vous devez être inscrit et connecté pour voir ce lien] said.

The [Vous devez être inscrit et connecté pour voir ce lien], the first for the 787 since it entered service last year, will be issued today and require checks of fuel-line connectors for an “unsafe condition,” the FAA said on the Federal Register’s website. Japan Airlines Co. and All Nippon Airways Co. both said they had repaired planes because of the fault.

The leaks, attributed to improperly installed couplings, could cause a plane to run out of fuel, an engine-power loss or a fire, the FAA said. Chicago-based Boeing issued a similar recommendation on Nov. 25, advising carriers to complete an inspection within seven days, according to the FAA. The planemaker delivered 33 Dreamliners, the first jetliner made chiefly of composite materials, through October.

Inspections are finished on about half of the 787s handed over so far, and Boeing is “taking appropriate steps to ensure proper installation on airplanes in production,” said [Vous devez être inscrit et connecté pour voir ce lien], a company spokeswoman. The couplings are in the pylons that support the jet’s two engines.

The FAA is requiring partial checks within seven days and what it estimates to be a full 10-hour, $2,712 inspection and potential repair within 21 days. It didn’t identify the 787s with the leaks beyond saying that they weren’t flown by a U.S. carrier.

ANA, JAL

All Nippon found and repaired the fault in “several” 787s, said Youichi Uchida, a spokesman. The carrier, the first Dreamliner operator, has a fleet of 16. Japan Air fixed two of its six 787s, said Kazunori Kidosaki, a spokesman. The two Tokyo-based airlines both said they no longer had any problems because of the fault. All Nippon delayed a flight in October because of a leak, Uchida said.

Boeing will “do a thorough evaluation as part of our internal process,” said Gunter, who declined to say whether there had been any incidents with the two Dreamliners in question or how the flaw was detected.

She also wouldn’t say whether the assembly mistakes occurred at Boeing’s wide-body plant in Everett, [Vous devez être inscrit et connecté pour voir ce lien], or at a newer factory making 787s in North Charleston, South Carolina, nor would she comment on how the errors occurred.

United Emergency

Yesterday’s emergency landing of a [Vous devez être inscrit et connecté pour voir ce lien] 787 because of an unspecified mechanical issue isn’t related to the fuel-leak directive, Gunter said.

United became the first U.S. airline flying the plane with a flight on Nov. 4 to the carrier’s headquarters city, [Vous devez être inscrit et connecté pour voir ce lien], from Houston. The incident yesterday involved a flight to [Vous devez être inscrit et connecté pour voir ce lien]’s Newark Liberty International Airport from Houston.

The 787 was 3 1/2 years late in making its commercial debut, after Boeing struggled with the composite materials and new manufacturing system that relies more on suppliers. Other manufacturing errors have been found during the Dreamliner’s development and entry into service.

In 2009, Boeing had to patch up several sections of about two dozen planes after finding tiny wrinkles in parts of the composite fuselages made by an Italian supplier.

Debris was left in the fuel tanks of a 787 test jet being built in January 2010, the same year that flaws in the tail sections were found in June and debris in an electrical panel led to an in-flight fire in November that grounded the entire test fleet for six weeks.

An engine component on a 787 fractured in July, spewing shards of metal out of the plane as it prepared for its first flight in [Vous devez être inscrit et connecté pour voir ce lien].