#Maintenance

Two recent events with damage to the passenger windows of the aircraft were reported to Airbus. Similar events also happened on non-Airbus aircraft. The damage was caused by the heat of spotlights used during promotional filming sessions. One of these events could have had serious safety consequences as damage was not detected on ground, and caused some window panes to detach from the aircraft during the next flight. This article describes this event in more detail and how to prevent heat damage due to exterior lighting. It also recommends checking the condition of the aircraft before it returns to service. 

With the start of the winter season in the northern hemisphere, it is a timely reminder to re-publish this article, initially published in 2018. Ice ridges on the lower nose fuselage can cause Computed Airspeed (CAS) values delivered by the ADRs to be lower than the actual airspeed which may lead to unreliable airspeed events. This article describes the potential effect on the aircraft’s systems from the takeoff phase and how to prevent such situation.

Each in-service aircraft is struck by lightning at least once per year, on average. Even if the level of energy of lightning strikes is high, their effects on an aircraft are limited.This article explains the lightning phenomenon and why aircraft are prone to lightning strikes. It describes how aircraft are designed to limit the effects of a lightning strike and ensure that the safety of the flight is not impaired. It also recalls several safety precautions to take in flight and on the ground, and what must be done when an aircraft is struck by lightning.

Performing similar maintenance tasks on redundant systems at the same time, or by the same person during a particular maintenance check, may lead to the repetition of a maintenance error. This creates a risk of simultaneous failure of the redundant systems when the aircraft is back into service.
This article provides best practices to reduce this risk and ensure that the benefits of redundancy of systems or components on the aircraft is not compromised.

Special tools or Ground Support Equipment (GSE) may be required to perform some maintenance tasks. Airbus provides a list of approved suppliers for GSE or tools in the Tools and Equipment Manual (TEM). GSE or tools from suppliers that are not listed in the TEM may be offered to Operators and maintenance organizations as alternatives. However, these alternative GSE or tools may not always be designed or manufactured to meet the technical, quality, and safety requirements of Airbus.

This article describes events where the use of unapproved GSE or tools led to serious incidents. It explains why it is important to only use GSE or tools from approved suppliers to ensure safe aircraft maintenance and operations.

Oxygen is a vital gas, but when combined with a source of heat and flammable material, it can cause a significant fire hazard. This risk increases in an oxygen-enriched environment and can even lead to an explosion. Oxygen servicing requires specific safety precautions to avoid any hazardous situations. This article explains how a fire can start in the presence of oxygen and highlights the safety precautions that must always be followed whenever working on oxygen systems.

Proper servicing of landing gear is obviously important to ensure proper landing gear operations during takeoff and landing. It is equally important to ensure proper retraction and extension to prevent potential interference with other aircraft systems in the case of abnormal landing gear conditions.
If the landing gear servicing tasks are not properly performed, issues can occur such as struts seized in a retracted position and strong vibrations that can affect the function of avionics equipment.
This article provides a description of best practices that maintenance crew can apply when performing the landing gear servicing tasks, with a focus on the shock absorber and the importance of regular lubrication.

All Brakes are subject to wear. Some brakes may also experience oxidation which can lead to brake rupture. In the case of a brake rupture or if brakes are too worn, the aircraft braking performance is reduced. This can result in a runway overrun if the full braking capacity is required such as during a rejected takeoff with an aircraft weight at or close to the maximum takeoff weight. Brake rupture can also lead to damage that can cause a brake fire due to hydraulic fluid coming into contact with hot parts.
This article describes carbon wear and oxidation phenomena. It recalls the maintenance procedures used to identify worn or oxidized brakes, flight crew procedures, and good practices to prevent brake wear and oxidation.

An aircraft fuel tank provides the perfect conditions for microbiological contamination to develop, especially when operating in hot and humid environments. Problems caused by microbiological contamination of fuel can range from inaccurate or erroneous fuel quantity readings to structural corrosion and engine fuel supply difficulties caused by clogged fuel filters.
As a result, if treatment is not correctly applied, microbiological contamination can also cause significant safety issues. This article describes why prevention is important and focuses on why it is essential to follow the maintenance procedures when treatment is required.

Several cases of uncommanded spoiler extension were reported to Airbus in recent years. Investigations showed that a high acidity level of the hydraulic fluid was a contributor to these events.
This article recalls the importance of checking the quality of the hydraulic fluid and describes the improvements made to the AMM/MP procedure to perform hydraulic fluid analysis and reduce buildup of acid in the fluid. It also recalls some good practices to prevent hydraulic fluid contamination during maintenance or servicing operations.

A number of engine Exhaust Gas Temperature (EGT) overlimit events at takeoff were reported to Airbus, including dual events leading to a significant increase in flight crew workload at low altitude.
This article recalls the importance of monitoring the EGT margin of each engine to detect any degradation in engine performance early, and provides recommendations to Maintenance, Flight Operations, and flight crews to prevent EGT overlimit events. It also reminds us of what to do in the case of an EGT overlimit indication at takeoff.

In the past few years, several events occurred involving landing with the Nose Landing Gear (NLG) wheels turned to 90° from the aircraft centerline.
The investigations identified the root causes, which were different for each event. Mitigating actions were developed and deployed accordingly.
This article describes the outcomes of investigations into several events of aircraft landing with NLG wheels at 90° and shows why they are not related. It also recalls the corrective actions and existing operational recommendations to prevent any recurrence.

A dedicated task force in Airbus Customer Support was created in response to the unprecedented impact of the global pandemic on our industry since March 2020. As there have been many aircraft grounded for an extended period of time, this letter provides Operators with the latest Airbus guidance on parking & storage of aircraft and to ensure their safe return to service.

A system reset is not always the quick fix that it may seem. Performing an inappropriate manual system reset in flight can seriously impair the safety of the flight. Multiple system resets on the ground without performing the necessary troubleshooting actions can also have serious consequences.
This article addresses when system resets are applicable and how to perform them correctly.

Flying on an aircraft with an incorrect aircraft technical configuration can cause unexpected system behaviors that could lead to an accident or a serious incident. This can occur when an aircraft is dispatched with a computer standard that is not authorized to be installed on that aircraft. Incorrect technical configuration or documentation can also create inconsistency between the documentation and the actual aircraft technical configuration.
This article recalls the key aspects of technical configuration management. It highlights the importance of checking the Part Number (P/N) of the software installed on data loadable computers and describes the tools that Airbus has developed to help Operators make sure that they install the appropriate P/N on their aircraft.

A significant number of missing wheel tie bolts have been reported to Airbus over the last 5 years. A few of these reports have described significant damage to the wheel or brakes.
Carefully checking the condition of the wheel tie bolts during aircraft walkarounds can allow detection of missing or damaged bolts and help to prevent serious incidents in service or during maintenance. Strictly observing the preventive maintenance practices, including planned inspection intervals, ensure that any damaged wheel tie bolts are replaced before they are at risk of failing.

Since the beginning of 2020, Airbus has received an increasing number of reports of unreliable airspeed events at takeoff due to Pitot probe obstruction. Despite the existing prevention means and the preflight exterior walkaround, takeoffs with obstructed air data probes may happen. This article highlights why it is so important for pilots to actively monitor the airspeed during the entire takeoff roll, to detect an airspeed discrepancy as early as possible, and safely reject the takeoff, if required to do so.

Operations Engineering Bulletins (OEBs) are temporary procedures published for flight crews. They must be applied only in specific conditions to ensure safe and efficient operations of the aircraft.
This article explains why OEBs are issued, the importance of communicating them to flight crews as soon as possible, and the importance for flight crews to comply with the OEB procedures. This article also stresses the importance of applying the available modifications that will cancel an OEB as soon as possible. Airbus provides support to Operators to assess and prioritize the implementation of service bulletin modifications that can remove applicable OEBs from their fleets.

Aircraft that were parked or stored due to the impacts of the COVID-19 sanitary crisis are progressively returning to the skies. It is in this context that Airbus has already received several reports of rejected takeoff (RTO) and in-flight turn back (IFTB) events due to unreliable airspeed. All of these events had positive outcomes thanks to the actions of the flight crews. It does however illustrate the challenges for returning aircraft to flying, after they are parked or stored, and if the maintenance procedures are not followed in all cases.
This is why we take this opportunity to share all of the available Airbus information and industry guidelines that can support Operators to ensure their safe return to the skies.

Facing the unprecedented and massive fleet storage worldwide which is needed in the current COVID-19 pandemic, Airbus has launched an active support to all operators about the grounding, parking and storage conditions.
To complement this on-going effort, this article aims at reminding some of the key safety considerations for a proper parking and storage. 

Safe refuelling operations require strict adherence to procedures and careful application of the safety precautions, not only by the refuelling operators but also flight crew, the cabin crew and the other ground operators.This article highlights the safety precautions that must be considered when refuelling an aircraft. It also describes supplementary tasks that are necessary if refuelling when passengers are on-board.

Cases of fuel spillage have been reported to Airbus on A320 family aircraft equipped with fuel transfer jet-pumps in the center tank.This article recalls the protections available against tank overfill. It explains why fuel spillage happened on the reported events and provides recommendations on how to avoid it.

Incorrect or incomplete application of the parking procedures at the end of a flight can lead to unexpected aircraft movement potentially resulting in injuries or significant damage from a collision with ground obstacles. Several cases of this type of event during maintenance are reported to Airbus each year.This article provides an overview of the parking brake architecture and explains the importance of checking accumulator pressure before applying the park brake, and then confirming there is sufficient hydraulic pressure at the brake unit. It also describes the safety enhancement available on A320 family and A330/A340 aircraft and gives recommendations for chock design and placement.

Signals from the Global Navigation Satellite System (GNSS) are one of the main inputs used for aircraft positioning or time reference for Communication, Navigation and Surveillance functions on-board most of the Airbus aircraft.
Operators report an increasing number of events related to the loss of GNSS signals due to Radio Frequency Interference (RFI) during operations in some areas of the world.
This article explains the causes of RFI, the effects on the aircraft systems and provides recommendations for flight and maintenance crews.  

Fan cowl door loss events are still reported to Airbus. In all cases, the fan cowl doors were not latched closed and secured following a maintenance task.
This article provides an update on the design and procedure improvements introduced on the Airbus fleet to prevent fan cowl door loss events.

It is of the outmost importance to make sure that escape slides’ maintenance is properly done so that they can deploy correctly when they are the most needed. This article recalls the importance of reporting scheduled and unscheduled slide deployment results to Airbus. It highlights the most common causes of unsuccessful slide deployments and provide recommendations to prevent them.

Emergency lights must illuminate when required for aircraft evacuations. If maintenance is not performed correctly, this can compromise the availability of the emergency lights.

Thousands of aircraft doors are opened daily, usually without incident. However, several events are reported to Airbus each year where residual cabin pressure caused a door to open violently, leading to serious injuries or aircraft damage. This article describes the available residual cabin pressure warnings, with their limitations. It recalls the recommendations for flight crew, cabin crew, and ground staff to take before opening an aircraft door and provides the safety precautions to take to avoid unintentional pressurization of the aircraft on ground.

The number of people injured when emergency escape slides are inadvertently deployed is low. Nevertheless, such events pose a threat to the safety of people in or around aircraft. They are also a cause of aircraft damage, and departure delays. This article looks at how Inadvertent Slide Deployments (ISDs) can be avoided, and presents a new solution available to prevent them.

Thrust reverser partial deployment in-flight events have been reported to Airbus which have had both a maintenance and an operational contribution.
This article describes a typical event, and provides a reminder of the recommended actions for the flight crew when an alert related to the thrust reversers is triggered at the gate or during taxi-out. It also provides maintenance recommendations to ensure correct thrust reverser de-activation task accomplishment.

All aircraft are designed, tested and certified to avoid the possibility of exceeding its structural strength. Operational thresholds or limits define the envelope for the load conditions in normal operations, and there are design margins to cope with abnormal or excessive loads on the aircraft if they are experienced in-flight or on the ground.  The Pilot’s report of high load events in the logbook is the starting point to commence an evaluation of the event to determine if the abnormal load has affected the structure or systems of the aircraft. Early reporting enables efficient evaluation of the event by maintenance personnel and it can allow the aircraft to more rapidly return to service when the required maintenance tasks are completed.

The dispatch under a Minimum Equipment List (MEL) item allows to dispatch an aircraft in a safe and airworthy condition when certain system functions or equipment are temporarily unavailable or inoperative, enabling the aircraft to continue earning revenue without compromising the safety of the flight.But, what are the MEL principles and are there good practices to think about when dispatching an aircraft with an MEL item in the tech log?

Cargo compartment linings are designed to provide an air-tight space, and are essential in protecting the aircraft and its occupants from fire and smoke.This article looks at how these composite components have come to play such an important role in Safety, and what can be done to make sure they stay in good condition.

There are currently around 33 million commercial flights a year and this figure is expected to double in the next 15 years. An aircraft arriving safely at its destination, and within a predictable time, is an expectation of both its crew and passengers. A growing number of apps are also available to the public that show an aircraft’s journey from departure to arrival, even providing seemingly real-time data for an aircraft’s speed, altitude and heading. With the technological leaps that have provided all of this information to hand and visible on our smart phones, it is not unreasonable for members of the public and media to ask, “How can we lose track of a large aircraft flying today?”

As moveable structural components such as control surfaces and landing gear doors age, wear of hinges and actuators can sometimes lead to airframe vibrations. These vibrations can cause noise and physical discomfort in the passenger cabin.To prevent further deterioration of components, the cause of vibration should be quickly identified and removed. For this, maintenance personnel require Flight Crew to make observations of the vibration using a Vibration Reporting Sheet (VRS).A clear understanding of how to complete the VRS is important before starting the observations. Some parts of the VRS require manual control inputs with Autopilot OFF and therefore cannot be performed in RVSM airspace.

Falling from an aircraft can cause serious injuries to people.Specific safety equipment is installed on Airbus aircraft, and when used correctly, can prevent falls from height. This article describes the available safety equipment for Airbus aircraft and recalls the basic safety precautions that will help to avoid falling from height injuries to everyone on the aircraft.

Pitot probes inlet obstruction will affect accuracy of the air data parameters calculated from its measurements such as the aircraft airspeed and Mach number. Pitot probes inlet obstruction on the ground can be caused by unexpected sources such as sand, dirt, dust or insect nesting activity. This is why it is important to think about when to install Pitot probe covers for an aircraft on the ground to protect its air data system performance.

Today, Lithium batteries play a barely visible, yet essential role in both our daily life and aviation alike. Manufactured and handled correctly, Lithium batteries are safe. But production failures, mishandling, or not being aware of their specific characteristics can have serious repercussions.

With the introduction of a data loading function on A320 Family aircraft Flight Control and Auto Flight computers, managing the aircraft configuration entered a new dimension. Flying a certified aircraft now requires understanding not only hardware Part Numbers, but also less immediately visible operational software ones.

Since the first A320 entry into service, very few events have involved undetected fuel quantity issues. Yet, coming across a situation where engines shut down by lack of fuel is a situation no one wants to experience.

No crew likes the idea of Unit Load Devices (ULD – containers and pallets) moving around in the cargo holds of their aircraft during flight. This type of occurrences may have multiple causes.

PDAs may be considered by some people as noncritical, especially when the part is small. Yet whatever the size, they may represent a potential safety risk. Preventing them must be the single objective of the combined and coordinated effort of a number of actors.

Composite materials are increasingly used in aircraft design. The A350 XWB is the most recent illustration of this trend. Yet if the benefits of composite materials are not in doubt for airlines, some questions still remain as to their potential effects on safety.

Non-adherence to the correct aircraft wash-ing/cleaning and painting procedures regularly generate safety events. This article will illustrate, through real in-service occurrences, that even activities performed primarily to improve the appearance of the aircraft and better display the airline logo may affect the safety of operations. The lessons learnt from these events are common: washing or painting an aircraft must be done according to the published procedures and using the correct equipment. These are  specified in the Aircraft Maintenance Manual (AMM), Structure Repair Manual (SRM) and Tool and Equipment Manual (TEM). 

In this article, Airbus would like to take you through a case study and use it to learn some lessons and share our safety first culture. The article is split into three distinct parts:The first will describe the eventThe second, targeted at flight crews, will discuss and develop the stabilization criteria and present a prevention strategy against unstable approaches. It will also insist on the need to use the appropriate level of automation at all times.The third part, targeted at maintenance personnel, will illustrate the need to always use the Aircraft Maintenance Manual (AMM) as the source document for maintenance operations.