Join me for a weekend read! 📖✈️

The different Airbus types have been certified at different times and comply with different certification rules.

🛫🧵

A major change occurred when the FAA published an amendment to FAR Part 25, known as "𝐀𝐦𝐞𝐧𝐝𝐦𝐞𝐧𝐭 𝟐𝟓-𝟒𝟐".

This amendment, which became effective on March 1, 1978, revised the takeoff performance standards and made them more restrictive.

Amendment 25-42 required accelerate-stop distance to include 𝟐 𝐬𝐞𝐜𝐨𝐧𝐝𝐬 𝐨𝐟 𝐜𝐨𝐧𝐭𝐢𝐧𝐮𝐞𝐝 𝐚𝐜𝐜𝐞𝐥𝐞𝐫𝐚𝐭𝐢𝐨𝐧 𝐛𝐞𝐲𝐨𝐧𝐝 𝐕𝟏 𝐬𝐩𝐞𝐞𝐝, before the pilot takes any action to stop the airplane.

It also introduced the 𝐀𝐜𝐜𝐞𝐥𝐞𝐫𝐚𝐭𝐞-𝐒𝐭𝐨𝐩 𝐃𝐢𝐬𝐭𝐚𝐧𝐜𝐞 𝐚𝐥𝐥 𝐞𝐧𝐠𝐢𝐧𝐞𝐬.

This revision resulted in longer accelerate-stop distances for airplanes whose application for a type certificate was made after amendment 25-42 became effective.

The Airbus #A320 was the first airplane to be certified under this rule, as no retroactivity was required.

And it was the last one too.

Although the airplane types were originally certified at different times, thus allowing the use of different amendments, both groups of airplanes were continuing in production and competing for sales and for use over some common routes.

Airplanes type-certified to the standards introduced by Amendment 25-42 were penalized in terms of payload, even though the takeoff performance might be better from a safety perspective, than the design of a competing airplane that was not required to meet the latest standards.

This disparity in airworthiness standards created an unfair international trade situation, affecting the competitiveness of a later design of the A320.

At the June 1990 annual meeting, the FAA & JAA agreed to jointly review the current takeoff performance standards to reduce the above-discussed inequities, without adversely affecting safety.

In March 1992, the JAA Notice for Proposed Amendment (NPA) 25B,D, G-244: "Accelerate-Stop Distances and Related Performance Matters" was issued, followed by the FAA Notice of Proposed Rule Making (NPRM) 93-8 on July 1993.

The rule changes proposed in the NPA and in the NPRM were essentially the same, and are better known as Post-Amendment 42.

NPA 244 and NPRM 93-08 (post-amendment 42) proposed the following rule changes:

• Replace the two seconds of continued acceleration beyond V1, with a distance margin equal to two seconds at V1 speed.

• Require that the runway surface condition (dry or wet) be taken into account, when determining the runway length that must be available for takeoff.

• Require that the capability of the brakes to absorb energy and stop the airplane during landings and rejected takeoffs be based on brakes that are worn to their overhaul limit.

After industry feedback, NPA 244 was incorporated into JAR 25 on October 2000 (change 15), whereas NPRM 93-08 was incorporated into FAR 25 on February 1998 (amendment 25-92).

The certification status of Airbus models is as follows:

• Pre-amendment 42 : A300, A300-600, A310

• Amendment 25-42 : A320*

• Post-amendment 42 : A318, A319, A320*, A321, A330, A340, A380, A350

*Some A320’s are certified with amendment 25-42, others with post-amendment 42

You can read the unrolled version of this thread here: https://typefully.com/chainsawrocks/987PnqP

Airbus Certification and Regulation Evolution

When aircraft are flown outside of their established operating limits – the flight envelope – and correction efforts are not made or occur too late, it can lead to loss of control in flight (LOC-I).

Safety innovation 🧵 on The Airbus flight envelope protection. 

High angle-of-attack protection: This protects against the risk of an aerodynamic stall, including in situations of wind shear, as well as during dynamic manoeuvres or in gusty conditions 

High-speed protection: The aircraft is protected against overspeed situations that may eventually result in potential control difficulties, as well as structural concerns due to high aerodynamic loads 

Pitch attitude protection: The pitch angle is limited between a minimum and a maximum value to prevent climbs or descents that are too steep. 

Bank angle protection: The bank angle and roll rate are limited to maximum values to prevent excessive banking, along with turns that are too steep, as well as the risk of the aircraft becoming inverted 

Load factor protection: The aircraft’s vertical acceleration is kept within safe limits for the airplane’s structure 

Low energy and alpha floor protection: They ensure that a suitable level of aircraft energy is maintained in flight, with corrections made via manual or automatic increases in engine thrust. 

LOC-I accidents have reduced by 89% for latest gen. of aircraft equipped with flight envelope protection

Today, fly-by-wire flight control &amp; flight envelope protection have become a norm. Beyond Airbus, examples include Boeing’s 777 &amp; 787, Embraer’s E-Jets &amp; the Sukhoi Superjet.

📹 credits : Manchester Flight Sim Centre &amp; Airbus

The Flight Envelope Protection

Performance varies over the life of all in-service aircraft, leading to slightly higher fuel consumption levels as an aircraft ages and leading to inconsistencies with the FMS trajectory prediction.

Mini 🧵on Optimize Suite
#A320

Performance Factor Optimizer (PFO) automatically computes the corrective fuel factor representing each aircraft in its current state of performance. This factor is updated in the FMS in the aircraft. This web-based solution automatically computes the “delta specific range”(DSR).


IDLE Factor Optimizer (IFO) enables to adjust the idle rate that the FMS uses for the descent predictions. The IDLE FACTOR ensures that IDLE rate corresponds to the actual IDLE thrust. This IDLE FACTOR is also updated in the FMS TO take into account the ageing of the aircraft.

When combined with the Airbus Descent Profile Optimization (DPO) every flight of each aircraft is optimized along the entire aircraft lifecycle.

These solutions bring savings per flight & operational benefits to fly fully optimised, resulting in both fuel & emissions savings.

https://twitter.com/chainsawrocks/status/1576133015394082816?s=46&t=6sLY3LuQETMmuymECoRGjQ

Optimize Suite for Aircraft Performance

Flight Management System (FMS) provides navigation for guidance, calculates fuel &amp; trajectories for the flight based on numerous parameters, including terrain, runway location &amp; airspace.

Airbus pioneered the FMS, which was integrated during the early 1980s on the first #A300’s. 

In testing, New APU flap intake for #A320

Old position below fuselage is prone to oil leaks, external pollution i.e de-icing/hydraulic fluid/fluid from drain mast being reingested causing poor cabin air quality

Relocating intake saves 85% of related maintenance
📸@FrankReardon1 https://twitter.com/FrankReardon1/status/1614264375048835072 

The click when engaging AP on #A320

When the autopilot is engaged a solenoid operated detent locks both sidesticks in neutral position. If👨‍✈️applies a force above threshold (5daN in pitch, 3.5 daN in roll) AP disengages, stick is unlocked &amp; the deflection is sent to the computers 

A safety innovation by Airbus introduced on A300 is the inhibition of slat retraction if angle of attack is high or speed is low, called - Alpha Lock.

On the #A320, alpha lock occurs if the angle of attack exceeds 8.5 degrees or the speed is at or below 148 knots. 

Over the last decade, there have been cases where a/c took off with incorrect trim or flaps, ⬆️risk of rwy overrun or tail strike

Airbus developed Takeoff Surveillance (TOS1 & TOS2) & Takeoff Monitoring (TOM) to provide additional safety to👨‍✈️during takeoff prep & takeoff roll
🧵

The « TO CONFIG TEST » pushbutton was first introduced on A300/A310 aircraft. When pressed, it checks the correct aircraft configuration for takeoff. If the aircraft configuration is not correct, the CONFIG light comes

TOS1 improves the checks performed on flaps & trim settings & adds a check of performance parameters entered in the FMS (aircraft weight and takeoff speeds)

The 1st step of Takeoff Surveillance (TOS1) was provided on #A320 family aircraft in 2009 and then on A330/A340 in 2013


TOS2 was introduced on A350 in 2018 & on #A320 & A330 aircraft in 2019. TOS2 checks that the aircraft is positioned on the intended rwy & the expected takeoff performance is compatible with the rwy distance available. However, the function is based on data entered in FMS by crew


The Takeoff Monitoring function (TOM) was first developed on A380 in 2018 and is now also available on A350. TOM monitors the acceleration of the aircraft during the takeoff phase and warns the flight crew if a lower-than-expected acceleration is detected.

While adherence to SOP ensures takeoff preparation is completed correctly regardless of whether an a/c is equipped with the TO Surveillance & Monitoring functions, focusing on the types of event that were reported shows that TOS & TOM would detect the majority of them.

TOS1 & TOS2 are available for the #A320, TOM is presently under feasibility study. The availability for retrofit depends on the exact aircraft configuration (FMS, EIS, ADIRU, and FWS standards)

It is important to remember that these Takeoff Surveillance functions are enhancements that act as an additional safety-net. They do not replace the correct application of SOP by the flight crew.

Credits : https://safetyfirst.airbus.com/takeoff-surveillance-and-monitoring-functions/

You can read the unrolled version of this thread here: https://typefully.com/chainsawrocks/O2C6pqf

Now offered on #A350, latest gen of Electro-Dimmable Window (EDW) darken twice as fast &amp; becomes 100 times darker than original version

They effectively block more than 99.999% visible light as well as infra-red energy (helps to keep cabin cooler &amp; reduce load on air-con system) 

Soon to be added to the #A320 will be the new “harmonized” Primary Flight Display(hPFD). An enhancement of the traditional ‘head down’ PFD, it provides

• FD pitch bar at takeoff
• Flight Path Director (Donut FD)
• Energy Chevrons
• Speed Delta
• Display selected FPA https://twitter.com/chainsawrocks/status/1583698716401074177 

The Flight references on PFD appear similar to HUD when TRK/FPA mode is selected to help the transition from Head up to Head down and keeping the symbology consistent with future Enhanced/Synthetic Vision Systems. 