AD 737 toutes versions

Bonsoir

Faisant suite à l'incident sur un -300 de Southwest (trou dans le fuselage) la FAA a préparé une réponse.

Inspection tout les 500 cycles à partir de la marque 35000

A noter qu'il existe un service bulletin de Boeing permettant de mettre en place un renfort local qui permet de s'affranchir de ces inspections.

C'est ici

http://www.flightglobal.com/articles/2010/01/12/337051/faa-firms-up-proposed-rule-prompted-by-southwest-fuselage.html

FAA firms up proposed rule prompted by Southwest fuselage hole
By Lori Ranson

The US FAA has finalised a rule it proposed in September 2009 requiring structural inspections of Boeing 737 classics for cracks after Southwest Airlines experienced an in-flight skin rupture and depressurisation on a 737-300.

As previously reported by ATI and Flightglobal, the incident occurred in July 2009 while the aircraft was enroute from Nashville to Baltimore. The aircraft landed safely in Charleston, West Virginia with a 43cm (17in) by 20cm hole in the skin on the upper section of the rear fuselage.

The inspections required in the final rule cover Boeing 737-300/400/500 series aircraft, and must be completed before the accumulation of 35,000 flight cycles or within 500 flight cycles of the rule's 16 February effective date. If no cracking is found, repetitive inspections are required at certain intervals not to exceed 500 flight cycles.

At the time of the Southwest incident, the affected aircraft had accumulated 42,569 cycles.

Carriers can be exempt from the continued inspections if they have installed an external doubler in a specific area on the fuselage outlined in a Boeing service bulletin issued in September of 2009.

FAA estimates 135 aircraft are affected by the new rulemaking.

Bonne soirée

Bonjour à tous

Inspection des compensateurs de profondeur sur 737.
2ème épisode après un premier AD

The US FAA has ordered a second round of inspections on elevator tabs for Boeing 737 Next Generation aircraft after a second in-flight vibration incident.

The new checks apply to 737s with line numbers between 2508 and 2707, a Boeing spokeswoman says. Aircraft flying extended twin-engine operations (ETOPS) missions must complete the inspections within six days, but all others have 12 days.

Boeing has clarified the instructions for the inspection criteria since another 737NG operator experienced an in-flight vibration event on 2 April.

The elevator tab for the same aircraft had previously been inspected in the first round of checks ordered after 15 March, Boeing says.

In that incident, a 737NG reportedly operated by Ryanair was forced to land in Brussels after severe elevator vibration damaged the tab control system.

According to Boeing, the vibration is caused by failed mounting lugs, which were provided by a supplier using incorrect tooling.

http://www.flightglobal.com/articles/2010/04/26/341109/re-inspections-ordered-for-737-elevator-tabs.html

1ère inspection suite à des vibrations sévères sur un avion de Ryan Air qui avait nécessité un atterrissage d'urgnece
A priori certaines inspections n'ont pas été suffisamment approfondies puisqu'un avion ayant été inspecté a subi à son tour des vibrations.

Défaut de fabrication sur la pièce d'un sous-traitant

Bonne journée

Bonjour !
Des AD à ntiroirs pour les élévators des 737 NG !

Inspections
Pieces, charnières, roulements
Re-inspections, les tôles autour ne tiennent pas assez ....
Nouvelles solutions en attente !
L'avion est léger, tout le monde le sait, et ce n'est pas toujours une qualité!

-------------- Du Seattle PI ----------------

http://blog.seattlepi.com/aerospace/archives/219311.asp

FAA expands inspections of Boeing 737s

Airlines must inspect Boeing Next-Generation 737 airliners for problems that can cause severe elevator vibration and possible loss of structural integrity and aircraft control, under a directive the Federal Aviation Administration issued Wednesday.

The directive applies to all U.S. 737-600, -700, -700C, -800, -900 and -900ER jets and is set to take effect Sept. 9. It adopts actions Boeing called for in a revised service bulletin last month.

The directive stems from two incidents in March and April, where Next-Generation 737s experienced vibrations, spokeswoman Julie O'Donnell said. "Both of those airplanes diverted and landed safely. There were no injuries."

After the incidents, Boeing issued a service bulletin and the FAA put out a directive requiring inspections (one-time in some cases, repetitive in others) of the inboard and outboard aft attach lugs of the left and right elevator tab control mechanisms and replacement of mechanisms with discrepancies, such as loose bearings. It allowed airlines to stop doing repetitive inspections if they replaced the mechanism with a new Boeing-built one.

The new order requires modified repetitive inspections of all the specified model airplanes, regardless of whether the mechanism has been replaced.

While there weren't any other incidents after the first two, Boeing analysis led to calling for the wider inspections, O'Donnell said. The problem is that layers of aluminum weren't clamped together sufficiently, resulting in wear of the tab control mechanism, she said.
------------------

JPRS

Bonjour,

http://www.gpo.gov/fdsys/pkg/FR-2012-09-12/html/2012-22392.htm

For airplanes having line numbers 1 through 3534 inclusive: Before the accumulation of 56,000 total flight cycles, or within 3,000 flight cycles after the effective date of this AD, whichever
occurs later, inspect to determine the part number of the attach pins of the horizontal stabilizer rear spar. A review of airplane maintenance records is acceptable in lieu of this inspection if the
part number of the attach pin can be conclusively determined from that review.

Inspection de tous les 737NG depuis le 1 au 3534 pour cause de revêtement anticorrosion et anti-friction défaillant sur des goupilles retenant le plan horizontal au droit de son longeron arrière

This AD was prompted by reports of an incorrect procedure used to apply the wear and corrosion protective surface coating to attach pins of the horizontal stabilizer rear spar. We are issuing this AD
to prevent premature failure of the attach pins, which could cause reduced structural integrity of the horizontal stabilizer to fuselage attachment, resulting in loss of control of the airplane.

Il me semble qu'airbus a eu récemment des déboires similaires

Les reliques du passé

http://www.reuters.com/article/2014/03/03/us-boeing-faa-safety-idUSBREA220AH20140303

U.S. aviation regulators on Monday plan to propose improving cockpit automation to help prevent pilot errors that have caused fatal airline crashes, according to a media report.

The Federal Aviation Administration wants cockpit automation fixes in nearly 500 Boeing Co (BA.N) 737 planes to ensure pilots have adequate safeguards if airspeed falls too low, particularly during landing approaches, the Wall Street Journal reported on Sunday.

Foreign regulators are likely to follow suit, the newspaper said.

The FAA was not immediately available for comment.

Boeing, in an email to Reuters, said the company "works closely with the FAA to monitor the fleet for potential safety issues and take appropriate actions."

The U.S. aircraft manufacturer said "the proposed rule mandates actions Boeing previously recommended to operators."

Pas le meilleurs article sur le sujet, mais bon

Il s'agit d'une lacune sur le 737 entre l'autothrust et l'automanette

lire
http://www.bea.aero/docspa/2012/f-an120720/pdf/f-an120720.pdf (page 9) et

http://www.onderzoeksraad.nl/uploads/items-docs/1748/Aanbevelingen_TA_EN.pdf

1. Boeing should improve the reliability of the radio altimeter system.

et du rapport
[quote
During the accident flight, while executing the approach by means of the instrument landing
system with the right autopilot engaged, the left radio altimeter system showed an incorrect height
of -8 feet on the left primary flight display. This incorrect value of -8 feet resulted in activation of
the ‘retard flare’ mode of the autothrottle, whereby the thrust of both engines was reduced to a
minimal value (approach idle) in preparation for the last phase of the landing. Due to the approach
heading and altitude provided to the crew by air traffic control, the localizer signal was intercepted
at 5.5 NM from the runway threshold with the result that the glide slope had to be intercepted from
above. This obscured the fact that the autothrottle had entered the retard flare mode. In addition,
it increased the crew’s workload. When the aircraft passed 1000 feet height, the approach was
not stabilised so the crew should have initiated a go around. The right autopilot (using data from
the right radio altimeter) followed the glide slope signal. As the airspeed continued to drop, the
aircraft’s pitch attitude kept increasing. The crew failed to recognise the airspeed decay and the
pitch increase until the moment the stick shaker was activated. Subsequently the approach to stall
recovery procedure was not executed properly, causing the aircraft to stall and crash.

]The problems with radio altimeter systems in the Boeing 737-800 fleet had been affecting several
airlines, including Turkish Airlines, for many years and were known to Boeing and the Federal
Aviation Administration of the United States of America.
Several airlines, including Turkish Airlines, regarded the problems with radio altimeter systems as a
technical problem rather than a hazard to flight safety. As a result, the pilots were not informed of
this issue.
It has become clear that the existing procedures, tests and routines applied by several airlines,
including Turkish Airlines, were not sufficient in order to resolve the problems with erroneous radio
altitude values.
The investigation failed to find a single cause for the origin of the erroneous radio altitude values.
Tests showed that the Rockwell Collins Enhanced Digital Flight Control System (EDFCS) uses radio
altitude values that are characterised as ‘non computed’ (unusable,) whereas this characterisation
should have prevented this. The operating software designed to compare the two radio altimeter
systems cannot be applied in the entire Boeing 737 NG fleet. The introduction of operating software
capable of making comparisons has failed to fully eliminate the undesired activation of the retard
flare mode.
Not all certified Boeing 737 operating software versions for the autothrottle and flight control computers
respond to an erroneous radio altitude signal in the same way. This situation is undesirable,
especially in cases where an airline is using several versions that respond differently and without
having informed its pilots.[/quote]

J'ai perdu le super lien que j'avais, mais si j'ai bien compris, il y a deux radio-altimètres un couplé à l'autopilote et un couplé à l'automanette.
Si l'un déconne, on n'est pas sûr de l'identifier ... puisqu'à l’origine les deux systèmes n'ont pas été liés...

A creuser et méditer