Hydraulics in aviation - what do the different colours mean.

Following on from yesterday's story about the A330 losing hydraulics in flight, we look at the different colours of hydraulics in aviation.

There are three continuously operating hydraulic systems, designated green, yellow and blue.

Each hydraulic system has its own reservoir. The reservoirs are pressurised by bleed air to prevent cavitation. The normal source is engine 1, but if pressure becomes low bleed air is taken from the cross-bleed duct.  

The green and yellow systems are normally pressurised by engine driven hydraulic pumps. These pumps have a upstream shutoff valve that cuts off the flow of hydraulic fluid when the associated engine fire button is pushed. The yellow hydraulic system may also be pressurised by an electric pump. This pump may be powered by either AC2 or external power. It operates automatically to partially pressurise the yellow system when the cargo doors are moved. It may be selected on manually using a switch on the hydraulics panel, in which case it fully pressurises the yellow system. 

The blue system is normally pressurised by an electric pump powered by AC1. This pump operates whenever AC power is available unless the aircraft is on the ground with both engines shut down. In this case it may be operated using the BLUE PUMP OVRD pushbutton on the maintenance panel.

Hydraulic power source of systems (excluding flight controls)
     Green                       Yellow                                  Blue
Landing gear            Nose wheel steering wheel         Emergency generator
Normal brakes         Alternate and parking brakes
Eng 1 reverser                 Eng 2 Reverser
Yaw damper 1                  Yaw damper 2

                                           Cargo doors

Batik Air Airbus A330 declares emergency landing in Madinah

Information has just been released that earlier this month, a Batik Air Airbus A330-300 travelling from Moroni (HAH/FMCH) to Medina (MED/OEMA) declared an emergency after suffering from a hydraulic leak. The Airbus aircraft is a six-year-old aircraft belonging to Indonesian carrier Batik Air and currently on wet lease to Saudi low-cost carrier Flynas. 

On the day of the incident, the 12th of June, the aircraft was operating as Flynas flight JT5146.

The A330 took off from Moroni's runway 35 at approximately 17:29 and flew the five-hour 3-minute journey to Medina when something happened during its approach. While descending toward Medina, the flight crew suddenly declared an emergency upon reporting that one of their three independent hydraulic systems, primarily the green hydraulic quantity, was reading zero. During the declaration of emergency, the flight crew stated they would not have normal brakes to work with during landing since it is one of the crucial systems powered by green hydraulics.

The flight crew continued their descent and safely landed on runway 18 at approximately 22:40. 

After the anxious arrival at Medina the widebody aircraft became disabled on the runway. While the cause of the green hydraulic leak has not yet been identified - albeit suspected to be from the nose gear, it seems the widebody is still undergoing maintenance and repairs, as flight schedules are still canceled. Hopefully, the Airbus widebody will get back in the skies soon.

Aircraft Information:

Owner: Batik Air

Operating as: Flynas

Code: XY/KNE

Aircraft: Airbus A330-343

Registration: PK-LEM

Serial number: 1832

Engines 2 x RR Trent 772B-60
First flew:14/10/2017
Age 5.7 years

Aeroflot Captain of 2019 crash that killed 41 people, goes to jail for six years

A Russian pilot has been sentenced to six years in prison after a plane he was flying made a rough crash-landing at a Moscow airport in 2019, killing 41 passengers, the general prosecutor’s office said.

Denis Evdokimov was operating an Aeroflot passenger flight from Moskva-Sheremetyevo Airport (SVO/UUEE), Russia to Murmansk Airport (MMK/ULMM), Russia on the 5th May 2019 when lightning struck the plane. He returned to the capital’s Sheremetyevo airport for an emergency landing.

Television footage showed the Sukhoi Superjet 100 bouncing along the tarmac before the rear part of the aircraft burst into flames. Forty-one out of 78 people aboard died, including two children. The surviving passengers escaped using the aircraft’s emergency slides.

“After the decision was made to return to the airport of departure, Evdokimov made, without observing the procedure for operating the aircraft, a very rough landing, allowing the aircraft to ‘bounce’,” the prosecutor’s office said.

“As a result, the main landing gear collapsed and the aircraft structure was destroyed with a spill and ignition of the fuel,” the office said.

Evdokimov was charged in 2019 with violating traffic safety rules resulting in the negligent death of two or more people. In addition to his prison sentence, Evdokimov is banned from operating aircraft for three years. He pleaded not guilty, Interfax reported. It was not immediately clear if he intended to appeal.

The aircraft was owned by VEB-Leasing Joint-Stock Company, the prosecutor’s office said.

Experts have warned of safety risks as Russian airlines, including state-controlled Aeroflot, are stripping jetliners to secure parts they can no longer buy due to Western sanctions.

Russian aviation safety has improved in recent years but accidents, especially involving ageing planes in far-flung regions, are not uncommon.

According to the Russian newspaper Novye Izvestia, there were more than 130 accidents involving civil and military aircraft in Russia in 2022, including 28 planes that crashed, excluding those related to the war in Ukraine.

Aircraft Information:

Airline: Aeroflot 

Code: SU/AFL

Aircraft: Sukhoi Superjet 100-95B

Registration: RA-89098

Serial Number: 95135

Engines: 2 x PowerJet SaM146

First Flew: 21/06/2017

Age: 6 Yrs. 

Brussels Airlines A320 blows tyre while taxiing

On Thursday I posted a story about a Scoot aircraft that lost a wheel on landing, well here is another airline that lost a wheel while taxiing.

Brussels Airlines flight SN2372 travelling from Vilnius Airport (VNO/EYVI) to Brussel-Zaventem Airport (BRU/EBBR) lost its left inner main gear tyre while lining up on the departure runway at Vilnius Airport. According to the airport, the incident affected 24 flights over the next few hours.

8 arriving aircraft were diverted. 9 departing flights were cancelled.

A passenger on board the flight was reported as saying an explosion was heard, rubbers splattered to the edges of the runway. At first, we were not allowed to move, and then the stairway approached, and everyone disembarked and was bussed back to the terminal.

Aircraft Information:

Airline: Brussels Airlines

Code: SN/BEL

Aircraft: Airbus A320 - 214

Registration: OO-SNI

Serial number: 1983

Engines 2 x CFMI CFM56-5B4/P
First flew13/03/2003
Age 20.3 years

Remembering Air India 182

AIR INDIA BOEING 787-8 VT-ANH (MSN 36276)

On the 23rd of June 1985, Air India flight 182 disintegrated in mid-air en route from Montreal-Mirabel International Airport, QC (YMX/CYMX), Canada to London-Heathrow Airport (LHR/EGLL), United Kingdom. It was at an altitude of 31,000 feet (9,400 m) over the Atlantic Ocean. The result of the explosion from a bomb being planted by Canadian Sikh terrorists. The remnants of the airliner fell into the ocean approximately 190 kilometres (120 miles) west-southwest of the southwest tip of Ireland, killing all aboard: 329 people, including 268 Canadian citizens, 27 British citizens and 24 Indian citizens. 

The aircraft took off from Montreal at 02:18 UTC. Its estimated time of arrival at London was 08:33 UTC. At 07:15 UTC, at FL310 over the Atlantic Ocean an explosion occurred in the forward cargo compartment, causing a rapid decompression. The aft portion of the aircraft separated from the forward portion before striking the water. The wreckage sank to a depth of 6700 feet.
From the wreckage retrieved no direct evidence was found of an explosive device. However, there is a considerable amount of circumstantial and other evidence that an explosive device caused the occurrence. Furthermore because an explosive device detonated in Tokyo the same day. Just 55 minutes before Air-India 182 crashed, A bag from CP Air Flight 003 exploded at Tokyo-Narita Airport, just 55 minutes before Air India 182 crashed. This was probably an interlined unaccompanied suitcase to be placed on Air-India Flight 301 to Bangkok.
Investigation determined that a suitcase was also interlined unaccompanied from Vancouver via CP Air Flight 060 to Toronto. In Toronto, there is nothing to suggest that the suitcase was not transferred to Terminal 2 and placed on board Air India Flight 181/182 in accordance with normal practice. The aircraft departed Toronto for Montreal-Mirabel and London with the suitcase unaccompanied.

The bombing of Air India Flight 182 is the largest mass killing in Canadian history, Canada's worst terrorist attack, the deadliest aviation incident in the history of Air India and was the deadliest act of aviation terrorism until the September 11 attacks in 2001.

Aircraft Information:

Airline: Air India

Code: AI/AIC

Aircraft: Boeing 747-237B

Registration: VT-EFO

Serial Number: 23634

Engines: 4 x PW JT9D-7A

Delivery Date: 30/06/1978

Boeing 747

There were 1551 747's built
This was the 14th loss
This was the 9th fatal accident
This was the 2nd worst accident (at the time)
and is the 5th worst accident (currently)

Scoot plane missing a wheel during stop in Taiwan

SCOOT BOEING 787-9 9V-OJE (MSN 37116)

A Scoot plane heading from Seoul (ICN/RKSI) to Singapore (SIN/WSSS) via Taipei (TPE/RCTP) was found to be missing a left nose wheel after it landed in Taipei during a scheduled stop on Monday morning.

Scoot said that flight TR897 detected a technical fault upon landing at Taoyuan International Airport.

“The flight which was originally scheduled to depart from Taipei to Singapore at 1.30am was subsequently cancelled,” it added. According to Scoot, more than 300 passengers were on board the plane.
Taiwanese media outlets reported that the left nose wheel fell off during the plane’s landing at 12.06am, after sensors detected abnormal tyre pressure before the plane’s descent.

“When the plane landed, the left tyre and metal rim on the nose gear were shorn off, leaving only the right nose tyre to keep the plane upright and moving,” reported Taiwan News.

Taoyuan International Airport was reported as saying there were no signs of the wheel on the runway or taxiway.

Aircraft Information:

Airline: Scoot 

Code: TR/TGW

Aircraft: Boeing 787.9

Registration: 9V-OJE

Serial Number: 37116

Engines: 2 x RR Trent 1000

First Flew: 12/06/2015

Age: 8 Yrs. 

Air New Zealand Boeing 787-9 returns to Auckland with damaged windscreen

AIR NEW ZEALAND BOEING 787-9 ZK-ZNJ (MSN 37966)

Air New Zealand travelers looking to head to Japan had their trip cut short on Sunday (the 18th of June), when the flight needed to turn around, just three hours into a ten-hour journey between Auckland (AKL/NZAA) and Tokyo's Narita (NRT/RJAA) due to a damaged windscreen.

The aircraft had departed from Auckland's runway 23L at 9.12am local, some 22 minutes behind schedule, and was three hours into the journey and passing over the northern islands of Vanuatu (Espiritu Santo) when damage was noted to the exterior layer of the windscreen. 

The pilots then made the appropriate decision to return to base, landing on runway 05R 3.05pm local where repairs could be made, and passengers could be re-accommodated.

Chief Operational Integrity and Safety Officer at Air New Zealand, David Morgan, noted:

"Windows on aircraft are made up of multiple layers to withstand damage, however, to ensure the safety of our customers and crew, it’s part of our standard operating procedure to return to one of our ports to allow our maintenance team to undertake repairs. Our team is currently working on rebooking customers on the next available service, and we thank our customers for their patience while we do this."

Passengers were advised mid-flight that they would be heading back to Auckland, and news quickly filtered through the cabin once flight attendants spoke to passengers mentioning it was due to damage on the windscreen. Whilst investigations are ongoing into how the damage was made on the Boeing 787-9, it is unlikely that it was due to impact from something in the air, given the flight was traveling at 35,000 feet.

Before its planned trip north to Japan, it had operated only one rotation the day prior. It was NZ145/146, a return trip from Auckland / Brisbane (BNE/YBBN). 

Aircraft Information:

Airline: Air New Zealand 

Code: NZ/ANZ

Aircraft: Boeing 787.9

Registration: ZK-NZJ

Serial Number: 37966

Engines: 2 x RR Trent 1000

First Flew: 10/08/2016

Age: 6 Yrs. 9 Mts.

According to Flightradar24, the aircraft performed NZ289 to Shanghai (PVG/ZSPD) last night.