A GE90-110B1 engine, mounted on a Boeing 777-200LR

Two in-flight engine shutdowns due to technical problems caused the U.S. FAA to issue an emergency Airworthiness Directive (AD) on certain GE90 turbofan engines.

The emergency AD was prompted by reports of two failures of transfer gearbox assemblies (TGBs) which resulted in in-flight shutdowns. Investigation has revealed that the failures were caused by TGB radial gear cracking and separation. Further inspections found two additional radial gears with cracks. This condition, if not corrected, could result in additional shutdowns of one or more engines, loss of thrust control, and damage to the airplane.

The AD only pertains to General Electric GE90-110B1 and GE90-115B turbofan engines with specific  TGB part- en serial numbers as listed in the AD. No later than five days after receipt of this emergency AD, U.S. airlines are not allowed to operate the airplane if more than one installed engine has a TGB serial number listed in the AD.

These engine models can be found on Boeing 777

More information:

FAA emergency AD 2013-10-52

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As a result of an in-flight, Boeing 787 battery incident in Japan, the FAA issued an emergency airworthiness directive (AD) to address a potential battery fire risk in the 787 and require operators to temporarily cease operations. Before further flight, operators of U.S.-registered, Boeing 787 aircraft must demonstrate to the Federal Aviation Administration (FAA) that the batteries are safe.

The FAA will work with the manufacturer and carriers to develop a corrective action plan to allow the U.S. 787 fleet to resume operations as quickly and safely as possible.
The in-flight Japanese battery incident followed an earlier 787 battery incident that occurred on the ground in Boston on January 7, 2013. The AD is prompted by this second incident involving a lithium ion battery. The battery failures resulted in release of flammable electrolytes, heat damage, and smoke on two Model 787 airplanes. The root cause of these failures is currently under investigation. These conditions, if not corrected, could result in damage to critical systems and structures, and the potential for fire in the electrical compartment.
On January 11, the FAA announced a comprehensive review of the 787′s critical systems with the possibility of further action pending new data and information. In addition to the continuing review of the aircraft’s design, manufacture and assembly, the agency also will validate that 787 batteries and the battery system on the aircraft are in compliance with the special condition the agency issued as part of the aircraft’s certification.

The emergency AD was also adopted by authorities of other countries operating 787 aircraft.  Airlines affected by the measure are LOT Polish Airlines in Europe, Air India, Ethiopian Airlines, Qatar Airways and Chilean carrier LAN Airlines.

Ethiopian Airlines said in a statement: “Ethiopian Dreamliners have not encountered the type of problems such as those experienced by the other operators. However, as an extra precautionary safety measure and in line with its commitment of putting safety above all else, Ethiopian has decided to pull out its four Dreamliners from operation and perform the special inspection requirements mandated by the US FAA.”

LAN Airlines stated on its website: “In compliance with the recommendation of the Federal Aviation Administration of the United States (FAA) and in coordination with the Chilean Aeronautical Authority (DGAC), LAN announces that it will temporarily suspend the operation of its three Boeing 787 aircraft.”

• FAA statement
• FAA emergency AD

Filed under: Airworthiness Directives by admin
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The European Aviation Safety Agency (EASA) issued an emergency airworthiness directive (AD) to ensure that flight crews, in case of  Angle Of Attack (AOA ) probes blockage on certain Airbus A330 and A340 models, apply the applicable emergency procedure.

The AD describes an event involving an Airbus A330 that experienced a blockage of all Angle Of Attack (AOA) probes during climb leading to autopilot disconnection and activation of the alpha protection (Alpha Prot) when Mach number increased.

Analysis showed that this aeroplane was equipped with AOA probes having conic plates, and it is suspected that these plates might have contributed to the event. Investigations are on-going to determine the root cause of this AOA probes blockage. The AOA conic plates can also be installed on A340 aeroplanes.

The conic plate AOA probes are used in favour of flat plates to improve the protection of AOA sensors from ice crystals.

The blockage of two or three AOA probes at the same angle may cause the Apha Prot of the normal law to activate.
Under normal flight conditions (in normal law), if the Alpha Prot activates and Mach number increases, the flight control laws order a pitch down of the aeroplane that the flight crew may not be able to counteract with a sidestick deflection, even in the full backward position.

This condition, if not corrected, could result in reduced control of the aeroplane.

To address this condition, Airbus developed a ‘Blocked AOA probes’ emergency procedure. The EASA AD AD requires an amendment of the Airplane Flight Manual (AFM) to ensure that flight crews, in case of AOA probes blockage, apply the applicable emergency procedure.

This AD is considered to be an interim measure and further AD action may follow.

More information:

• EASA AD2012-0258-E

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File photo of the L1 door of an Airbus A300-600 (photo: Harro Ranter/ASN, 2006)

The European Aviation Safety Agency (EASA) has issued an Emergency Airworthiness Directive (AD)  requiring the inspection of portable oxygen cylinders in certain overhead stowage compartments of Airbus A300-600 and A310 aircraft.

During maintenance, an operator found that one portable oxygen cylinder assembly had slipped from its bracket inside a one-frame overhead stowage compartment located near door L1. The investigation results indicated that the cylinder assembly had fallen behind the compartment through a cut-out on the comparments’ outboard panel and damaged some electrical wires, resulting in arcing, melted wires, partial burn stains on the and on the cylinder assembly inside of the fuselage.
This condition, if not detected and corrected, could possibly result in an uncontrolled fire in the affected area.

Therefor EASA issued the Emergency Airworthiness Directive (AD), requiring a detailed visual inspection of portable oxygen cylinder assemblies located in one-frame overhead stowage compartments of Airbus A300-600 and A310 aircraft.

More information:

EASA AD No.: 2012-0232-E (PDF)

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An All Nippon Boeing 787 with Trent 1000 engines (Photo: eipu – CC-by-nc-sa

The European Aviation Safety Agency (EASA) issued an emergency airworthiness directive, requiring replacement of specific gearbox assembly models on Rolls-Royce Trent 1000 engines.

EASA reports that transfer gearbox (TGB) failures occurred during Trent 1000 engine testing.
Engineering investigation determined that the crown wheel gear of the TGB had failed due to corrosion. The latter was the result of a change in a step of the manufacturing process. It was possible to identify a list of potentially affected
gearbox assemblies.
Therefor, an emergency AD was issued to require replacement of the affected gearbox assembly with a serviceable part. This AD also prohibits installation of an affected gearbox assembly.

The Trent 1000 engines are known to be installed on, but not limited to Boeing 787 series aeroplanes. The only airline currently operating 787 planes with Trent 1000 engines is All Nippon Airways.

By the time the  emergency AD had been issued, July 25, All Nippon had already grounded five planes on July 22.

More information:

• EASA AD 2012-0137-E (PDF)
• ‘ANA grounds Dreamliners, citing engine corrosion risk‘ (Reuters)

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Airbus A380 file photo by Jerome_K

The  European Aviation Safety Agency (EASA) publishes an updated Airworthiness Directive, extending the inspection for Airbus A380 wing cracks to the entire fleet of 68 operational aircraft.

EASA had already issued EASA AD 2012-0013 on January 20, 2012,  ordering inspection of certain Airbus A380 aircraft for the possible presence of cracks in the wing rib feet. The outcome of these inspections prompted EASA to extend the checks to include all A380′s.
Affected airlines are Emirates which now has 20 A380s in service, Singapore Airlines (15), Qantas (12), Lufthansa (8), Air France (6), Korean Air (5), and China Southern (2).

This new AD, EASA AD 2012-0026, supersedes the previous AD.

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The European Aviation Safety Agency (EASA) issued an Airworthiness Directive (AD), ordering inspection of certain Airbus A380 aircraft for the possible presence of cracks in the wing rib feet.

The AD states:

Following an unscheduled internal inspection of an A380 wing, some rib feet have been found with cracks originating from the rib to skin panel attachment holes (Type 1 cracks according to Airbus All Operator Telex (AOT) terminology).

Further to this finding, inspections were carried out on a number of other aeroplanes where further cracks have been found. During one of those inspections, a new form of rib foot cracking originating from the forward and aft edges of the vertical web of the rib feet has been identified (Type 2 cracks according to Airbus AOT terminology). The new form of cracking is more significant than the original rib foot hole cracking. It has been determined that the Type 2 cracks may develop on other aeroplanes after a period of time in service.

This condition, if not detected and corrected, could potentially affect the structural integrity of the aeroplane.

For the reasons described above, this AD requires a Detailed Visual Inspection (DVI) of certain wing rib feet. This AD also requires reporting the inspection results to Airbus.

This AD is considered to be an interim action to immediately address this condition. As a result of the on-going investigation, further mandatory actions might be considered.

The cracks were discovered by Airbus engineers while performing repair work to a Qantas A380 that had suffered an uncontained engine failure near Singapore’s Changi Airport. Singapore Airlines also discovered some cracks in on the L-shaped feet of the wing ribs. The feet attach the rib, a vertical fixture, to the cover of the wing.

On January 9th a spokesman for the Australian Licensed Aircraft Engineers Association demanded that all A380 aircraft should be grounded for inspections. Airbus reported that all planes were safe to fly and that the cracks did not pose a safety threat.

More information:

• A380 wing cracks ‘really is not a safety issue’: head engineer (Sydney Morning Herald, 6 Jan 2012)
• Singapore Air Checks A380s After Cracks Found (Bloomberg, 20 Jan 2012)
• EASA AD 2012-0013

Filed under: Airworthiness Directives by Harro Ranter
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The European Aviation Safety Agency (EASA) is proposing an Airworthiness Directive for an Airbus A330/A340 Flight Control Primary Computer (FCPC) software update in the wake of the fatal accident involving Air France flight AF447.

EASA states that it has been determined that, when there are significant differences between all airspeed sources, the flight controls of an Airbus A330 or A340 aeroplane will revert to alternate law, the autopilot (AP) and the auto-thrust (A/THR) automatically disconnect, and the Flight Directors (FD) bars are automatically removed.
Further analyses have shown that, after such an event, if two airspeed sources become similar while still erroneous, the flight guidance computers will display the FD bars again, and enable the re-engagement of AP and A/THR. However, in some cases, the AP orders may be inappropriate, such as possible abrupt pitch command.
In order to prevent such events which may, under specific circumstances, constitute an unsafe condition, EASA issued AD 2010-0271 to require an amendment of the Flight Manual to ensure that flight crews apply the appropriate operational procedure.

Since that AD was issued, new FCPC software standards have been developed that will inhibit autopilot engagement under unreliable airspeed conditions. The proposed AD requires software standard up-grade of the three FCPCs by either modification or replacement. The Proposed AD will be open for consultation until 30 August 2011.

More info:

• EASA PAD No.: 11-081

Filed under: Airworthiness Directives by Harro Ranter
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Transport Canada issued an emergency airworthiness directive regarding wing to fuselage attachment joints on DHC-8-400 aircraft models.

Transport Canada reports that there have been three in-service reports of cracked barrel nuts found at the front spar locations of the wing to fuselage attachment joints. Additionally, three operators have reported finding a loose washer in the barrel nut assembly. Failure of the barrel nuts could compromise the structural integrity of the wing to fuselage attachments.
Preliminary investigation determined that these cracks are due to hydrogen embrittlement.
The AD mandates an initial and repetitive detailed inspection of the barrel nuts.  The AD applies to all DHC-8 aeroplane models 400, 401 and 402, serial numbers 4001 and subsequent that have accumulated 1900 or more total hours air time or 12 months or more in service since new

More information:

• http://www.caa.co.uk/docs/33/20110721TCADCF201124.pdf

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The European Aviation Safety Authority (EASA) issued an emergency Airworthiness Directive (AD) effecting specific Airbus A330 and A340-200/-300 aeroplanes. EASA requires reduction of the existing main landing gear (MLG) bogie beam life limits and replacement of each MLG bogie beam that has already exceeded the new limit.

During ground load test cycles on an A340-600 aeroplane, the MLG bogie beam prematurely fractured.
The results of the investigation identified that this premature fracture was due to high tensile standing stress, resulting from dry fit axle assembly method.
Improvement has been introduced subsequently with a grease fit axle assembly method.
Analysis was performed on other bogie beam with dry fit axles. It has been determined that MLG bogie beams with specific part numbers  are more likely to suffer from standing stress generated by dry-fit axles because these bogie beams are stiffer between the axle sockets. These two part numbers are fitted on A330, A340-200 and -300 series aircraft.

Fracture of a MLG bogie beam under high speed could ultimately result in the aeroplane departing the runway, or in the bogie detaching from the aeroplane, or MLG collapse, which could cause structural damage to the aeroplane and injury to the occupants.

More information:

• EASA Emergency AD No.: 2011-0122-E 

Filed under: Airworthiness Directives by Harro Ranter
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