A Terrible DOUBLE Mistake!

sometimes the chain of events needed to cause an accident can be so strange that it seems almost comical but these Pilots struggling to keep their Airbus a321 in the air were certainly not laughing stay tuned the aircraft involved in this truly fascinating story was an 11 year old Airbus a321 operated by Titan Airways it was equipped with two CFM 56 5b3 engines which is a variation of the engines fitted to the Boeing 737-800 that I normally fly in the Autumn of 2019 a fuel sample had been taken from the aircraft's fuel tanks and sent to a laboratory for routine analysis when the results came back they showed that the tanks contained moderate microbiological contamination meaning that fungi or similar microorganisms had started to build up this is basically similar to what can happen in a swimming pool if you aren't careful the maintenance procedure for that level of contamination stated that a second test was needed within a few months to confirm the results the aircraft was scheduled for a bigger maintenance check in February of 2020 and it was decided that if the analysis came back with the same result to them a special biocide shock treatment would be performed to fix it so said and done in February the aircraft was flown down to the base of the approved maintenance organization the Amo that Titan had contracted which was situated in Larnaca Cyprus this ammo had recently started up and was still accruing tooling and workspace for their engineers at this point and because of this being the startup phase the workload was reported as quite high with several aircraft being worked on at the same time on a limited workspace as they were doing the work on the Titan Airways Airbus the engineers came across a problem with a modification that they needed to perform on a couple of passenger seat power supplies this meant that the work started falling behind schedule creating some time pressures on the involved Engineers the scheduled fuel tank analysis came back again indicating moderate contamination which meant that the engineers now also needed to perform the tank shock treatment one of the engineers was assigned to do this job by himself and this was going to be the first time that he did it but it looked at least on the surface like a pretty easy job a biocide called Castle was supposed to be used and the engineer started looking through his manuals for the correct procedure to follow it soon became clear that the instructions were quite vague the bio side was supposed to be added pre-mixed at a concentration of 100 PPM by volume of jet fuel into the affected tax the engineer whose first language was not English was not familiar with the term PPM and he started to look for an explanation for it in the manuals but he couldn't find any he also tried finding a colleague to ask but there was no one around so he did the next best thing he went to the internet and found a PPM converter there that he could use instead according to the calculations that he made using that converter he would need to add about 30 kilos of cathode to each tank containing about 6 200 kilos of fuel this didn't look so strange to him since the packages of cathon came in those kind of quantities but the problem was that if he would have calculated this correctly the correct quantity was actually less than one kilo per tank this meant that he was now about to add almost 38 times more cathode into each fuel tank than what was actually needed and on top of that the packaging instructions stipulated that the castle needed to be added to the fuel pre-mixed as in already blended into the fuel but that fact was not particularly well highlighted so the engineer went into the stores they had in the hangar and acquired they needed cathon and he then decided to add it to the fuel from an access point on top of the wings while the refueling was going on that seemed to be the easiest way to do it and he didn't have access to any dedicated tooling to add it in any other way this had two immediate consequences Not only was the concentration of the captain way higher than the highest approved level but it also didn't get properly mixed and since the specific gravity of the cathode was higher than the fuel it now sank to the bottom this created a layer with even higher casting concentration at the bottom of the tanks near the engine fuel inlets now this type of mistake might sound incredible but it was later found out that the poor instructions around this procedure had actually led to similar mistakes happening in other maintenance sites as well the cast on treatment was one of the last maintenance actions that the aircraft had to undergo so on the 24th of February 2020 it was signed off and flown back to London Stansted Airport to start operating with passengers again during the ferry flight back to the UK the operating crew didn't report any issues with the engines and the flight went smoothly in the morning of the 25th of February a crew consisting of two pilots were scheduled to Ferry the aircraft empty from London Stansted over towards London Gatwick a short hop of about 20 minutes or so after that first flight the aircraft will be taken over by another crew who would operate a passenger flight from Gatwick down to Krakow in Poland and then back again later in the evening around midnight I saw the original crew would then Ferry it back to Stansted again it was a beautiful winter day with clear skies and light winds perfect for a short hop like this and I would suspect that the pilots were probably looking quite forward to it the captain was 28 years old and had a total flying experience of just over 5 000 hours of which almost all of it 4855 hours were flown on the Airbus A320 family he was joined by a reasonably new first officer who was 38 years old with 1245 hours of Total time and 1083 hours on the type after the pilots had reviewed the pre-flight documentation they walked out to the airport and started getting ready for departure the captain checked the technical status of the aircraft which was good with no open maintenance items this was of course to be expected since the aircraft had just arrived back from a major overhaul at times instead of 5 20 in the morning the pilots were ready and received clearance to push back and start their engines the first officer who was pilots flying on this leg first started engine number two as the pushback was beginning that engine started without a problem but when he tried starting Andy number one an ecam message popped up indicating that the high pressure fuel valve had failed in the closed position ecam also instructed the pilot to stop the start attempt and to shut the engine down the captain followed the instructions and then got into contact with the company maintenance department to get advice on how to proceed and they told him to do another start attempt and to get back to them if that would also fail this is a pretty standard way of doing things a single valve indication doesn't necessarily indicate any kind of damage especially early in the morning when the components might be called so to try and restart the engine would be the logical thing to do on the second attempt the engine started without the problem and there were no new Eco messages so the pilot concluded that the aircraft was working perfectly fine they resumed normal procedures tax it out and took off for their short flight over towards Gatwick the flight was completely uneventful and after he had landed and taxed in they were met by the next crew who was going to operate the following flight down towards Krakow the pilots informed the oncoming crew about the start issue that it had on engine number one in Stansted and what engineering had advised them to do now we captains always try to give a verbal Handover like this especially if something unusual have happened this increases the next crew situation awareness and might Prime them for any failures that might reappear the new crew thanks for the information and then took over the aircraft the passengers were boarded and the aircraft pushed back and started their engines without any kind of problems this time they then tax it out for takeoff from a 2-6 left in Gatwick the following flight over toward Krakow was completely uneventful but unbeknownst to the crew the extreme concentration of cathon in the aircraft fuel tanks have now started to affect some components inside both Indians fuel systems the engines are fed the fuel through a device called a hydro mechanical unit or an HMU this unit uses pressurized fuel to operate several valves inside the engine to let the correct amount of fuel through to each burn chamber because of the nature of dealing with highly pressurized Fuel and to avoid leaks the valves are moving with absolute precision and must be able to move smoothly and easily in order for the HMU to function well the cathons launch at the bottom of the tanks had during these first three flights started to make its way into the hmus depositing itself on the components inside there in the form of a gelatin-like substance it also obviously was injected into the fuel cell but since Chasm was designed as a fuel additive it didn't much affect the way that the fuel burned like for example what water would do it did however affect the burn process slightly in two different ways one the sludge which didn't get properly burned got partly deposited inside of the burner cups of the engines and two since decathlon included small quantities of different mineral salts when these burned they created a wide residue on the high pressure turbine blades of the engines now that's worth remembering after the aircraft had landed in Krakow the crew had a short break before they started preparing for their return flight and it's on that flight that things will start to become really interesting and talking about the interesting here comes a short message from my sponsor you guys 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code Mentor pilot again that's curiositystream.com Mantra pilot to save 25 that's just 1.25 cents per month for some of the best non-fictional content out there thank you curiosity stream now back to the video the pilots have now flown a full sector without any kind of problems but they still remember the starting issues that the first crew had told them about this meant that they were really alert when they received their clearance to push and start for their return flight from Krakow India number two started normally but when it was time for engine number one an engine 1 HP valve ecam warning again occurred prompting them to abandon the start attempt this was the same warning that the earlier crew had experienced in Stansted and the captain remembered that the maintenance had told those Pilots to try a second start attempt Pilots now try to do that as well but with the same results the same warning came up again now there were no limits set for the number of starter terms that you could do on CFM 56 engines depending of course on what's causing the failed starch they're only recommendations that existed were on the starter engine cooling time so after the crew discussed it a bit they decided to attempt a third start during this third attempt they received a new Eco message stating engine number one start fault engine 1 stalled but this message was Then followed by a new start in progress message meaning that the engine was taking care of this automatically the engine subsequently started normally with no further ecam warnings given that the ecam warnings only affected the engine start sequence and the engines were now both running fine the pilots decided that it was safe to continue the flight now I actually fully understand the way that the part is recent here at this point there was nothing indicating a serious malfunction of the engine and absolutely nothing pointing towards an issue with the fuel the way fuel contamination normally manifests itself is via a fuel filter bypass warning indicating that the fuel filters have been clogged followed by issues with potentially both engines and the APU and in this case the issue had only showed up during the Indian start sequence and only on named number one after the start both engines were running just fine just like they had been during the previous flight so that meant that around 2020 UTC Titan Airways flight 112 took off towards London Gatwick the aircraft climbed normally up to their cruising altitude and during the climb the captain contacted the Titan air with maintenance department via a cars and notified them about the issues they had and experienced during the engine start the flight proceeded normally and the pilot started preparing themselves for a standard ILS approach into Runway 2-6 left in Gatwick the first officer was part of flying and around 2130 the aircraft started its initial descent now London Gatwick is a very busy airport and often require long vectors and intermediate level offs before the Final Approach can be started so when the aircraft reached flight level 140 that's 14 000 feet they were told to maintain that level for a while and because of that they had to increase their engine trust slightly to keep their speed and as soon as they did that light vibrations could be felt throughout the aircraft but it was hard to pinpoint exactly where the vibrations were coming from the pilot looked at the engine instruments who also indicated some light vibrations but they were well within approved values after a while they received further descent clearances and the vibration seems to disappear when the trust was reduced and then they would come back as soon as the trust was increased for whatever reason on two occasions during The Descent the ecam displayed also flickered on indicating an engine 2 stall but the indications lasted for less than a second each making it very hard for the pilots to see which engine was affected now an engine stall can appear for many different reasons the most common ones are bird strikes or ingestion of ice from the fan blades these engine stalls happen when pressure builds up in the wrong place inside of the engine core changing the flow of air causing the compressor blades to stall they often happen very quickly causing a pumping sound and when the stall happens the forward thrust is greatly reduced these engine stalls often repeat themselves several times especially if they're caused by damage and they can often be solved by reducing the engine trust below the onset value and if that doesn't help the engine would have to be shot down to save it from damage the crew who still weren't sure about which engine was affected discussed what to do and the captain said that if the indication would appear again they would follow the ecam instructions declare a Mayday and then continue into Gatwick which they were already prepared for they then requested continues to send clearances to avoid having to increase Indian Trust and that seemed to do the trick as the vibrations initially just disappeared but once the aircraft was established on approach and the crew selected geared down the vibrations came back but without any Associated ecam warnings the captain decided to just continue the approach and the aircraft landed normally just a few minutes later after the landing when reverse trust was selected the cabin crew reported a strange pumping sound to the pilots once the aircraft had stopped at the gates the captain phoned up their maintenance department and informed them about what had happened during the flight he also filled in the information about the indicated engine stall in the aircraft tactical logbook and once you've done that once you've filled anything into the logbook the aircraft will not be able to depart until a qualified engineer has looked at the problem and potentially fixed it and in order to get this done an experienced line engineer who was working for a third-party maintenance firm not by the airline itself was called out he came to the aircraft and talked to the pilots and then he downloaded the post-flight report pfr from the aircraft computers a pfr is basically a report of all indicated faults during the flight and it showed the engine stalled warning on engine number two together with the earlier start issues there were no Tech log entries regarding the start issues and even though he saw that they had occurred he didn't think that they were related and he had not been instructed by the base engineer to check that out any further and now comms may be the most ironic plot twist in this entire story because the line engineer now took the results of the pfr and went into his maintenance computer to look for the correct troubleshooting Guidance the company that he was working with was in the middle of changing between one engineering software to another but the new improved software had not yet been fully installed the line engineer knew that the aircraft in question had CFM 56 engines but he was not aware that Titan Airways recently also had started using a321s equipped with the new leap 1 engines also made by CFM this meant that when he went into the computer system he didn't filter using the aircraft individual instead he used the fault code received from the pfr and then chose an engine saying CFM from the list that appeared the problem was that the CFM 56 was indicated as cfmi and the new leap engines as cfml and this meant that engineer now without even noticing it shows the troubleshooting procedure for the wrong type of engine in the case of the leap engines only a simple outside visual inspection was required after an indicated stall but if you would have chosen the procedure for the CFM 56 centers the correct engines he would have also needed to perform something called a boroscope inspection a boroscope inspection means looking with a small camera inside the engine at among other things the turbine blades and do you remember what it would have seen if you would have done that yes white residue from the burned cattle if you would have seen that it would most likely have stopped this chain of events completely but instead the holes of the Swiss Cheese model just kept lining up [Music] the line engineer now performed the required outside visual inspection which didn't show any issues and then proceeded to sign off the engine as fully serviceable and no further action was taken the pilots who had flown the aircraft in the morning had now returned to take the aircraft back to London Stansted again they had been briefed by the previous crew about their ongoing starter issues with Andy number one and the new Indian stall indications from India number two the outgoing Captain also explained that the maintenance department had been made aware and that they were now working on the engine now the fact that both engines had now showed issues would likely have made the ongoing Captain quite cautious he called up the maintenance control to discuss the issue and they told him that the starter issue likely had to do with an igniter and as long as the engine started it would not cause him any further problems when it came to the other engine it was being investigated as they spoke but no one had made any connections between the two issues the captain then also spoke to the line engineer who was working on the aircraft and he also looked at how he was working which he thought looked meticulous and professional this calmed him down but he still proceeded to brief the five cabin crew members who were going to fly with them over to Stansted about the issues and told them to be very vigilant these actions are all Hallmarks of a very professional Captain who is following procedures and keeping his crew informed it is actually really nice to see once the line engineer had given the all clear and signed off the tech log the crew boarded the aircraft and started preparing it for departure the captain was going to be Pilot Flying for the return leg and at time 23 49 the crew requested pushback and start during the pushback Andy number two started normally but again engine number one started having issues the first start attempt was abandoned because of an indicated igniter fault and the second one gave an engine fail warning together with a consider a re-light ecam message before the third re-light the captain called the base engineer who actually authorized a third start attempt the captain advised the pushback crew that he would be returning to the stand if this the third attempt also failed and initially it seemed to become the case because an Indian fail alert came back again but then it disappeared and the engine started normally the captain who was still in contact with the base engineer at this point asked to get his opinion and the engineer again said that he thought it was likely an igniter issue and the number two had been checked by the other engineer and now appeared to be running smoothly the captain and the base engineer agreed that the crew would do an engine run-up on the runway to verify both engines were running smoothly prior to departure the two pilots now discussed the situation and from their view it looked okay at this point and since it was only a short flight in controlled airspace and in great weather they decided that they were happy to continue but they also believed that they would monitor the engine instruments carefully the first officer requested taxi and the aircraft started taxing out to the holding position for only two six left once at the holding point they made a short engine run-up which went fine and then reported that they were ready for departure once they receive their takeoff clearance the pilots verified that the cabin was secured and then entered the runway for a second 15 seconds long engine run-up this second run-up also showed stable and normal engine indications so at the time zero zero zero nine nine minutes after midnight Titan Airways flight Alpha Whiskey Charlie 4-1-1 whiskey started its takeoff run the rotation was completely normal but as soon as the aircraft climbed through 500 feet ending number one started stalling and surging violently since takeoff trust was set the temporary and irregular loss of trust with each search made the aircraft Euro violently to the left which the captain then counteracted with some right rudder dealing with engine surges like this can actually be much more tricky than dealing with a regular engine failure as the amount of Rudder you need to add will vary depending on the thrust output of the engine as the captain was struggling to control the aircraft the cabin crew in the back saw Flames coming out of engine number one and they immediately attempted to contact the pilots to let them know about it now Flames like this are not uncommon in the case of engine stalls and they are not indicative of an engine fire the Flames are simply a result of the uneven airflow through the engine core as a result of the Stalls the engine N1 went as low as 40 during a 25 second period and the captain decided to reduce the number one trust lever back to idle in order to make the aircraft easy to control and hopefully stop the surging there were no ecam alerts about this issue initially the pilot now made a Mayday call to air traffic control and requested an immediate return to Runway 2-6 left the captain also made a quick emergency PA to the cabin crew letting them know about the need for a potential evacuation of the landing and since the crew had been so well briefed before the flight on the earlier issues they reacted immediately and started to prepare that's the benefit of a good pre-fight briefing after the MayDay call the captain initiated an immediate right-hand turn to downwind for Runway 2-6 left he leveled the aircraft off at a maximum altitude of 3600 feet and instructed the first officer to start preparing the flight management computer radios and the rest of the cockpit for landing which the first officer also did but when the crew started their initial distance still on downwind they were faced with the next problem an e-com alert popped up advising them that engine number two their only remaining engine was now also stalling meaning that they might soon find themselves without any engines at all this prompted the captain to gently move the number one trust lever up from the idle position and then reduce the Trust on ending number two in order to try and maximize the available Trust he found that if he kept the engines at around 49 and won they both seemed to run reasonably well but there was no telling how long that would actually be the case now as a reference 49 and one is below the normal approach setting needed for landing in an aircraft at normal weight but for an aircraft almost empty like this aircraft was it likely would have been enough to keep the speeds throughout the approach configuration now the crew did not delay the approach instead they started configuring the aircraft and intercepted an approach at nine miles final and they kept a constant shallow descent to keep the trust as low as possible the captain then decided to Fly Above the normal Glide slope in order to have some extra energy to reach the runway in case both engines would suddenly fail which certainly there was a real possibility that they might do again this is a very wise and thinking outside the box decision by the captain made under intense stress and time pressure the first officer also did a great job here supporting the captain as he was hand flying the approach at time zero zero twenty only 11 minutes after they had taken off the aircraft landed safely on robot 2-6 left the crew used reverses as per normal procedures and they appear to be working fine but they were met by the fire department to attended to the aircraft of the landing and they reported that the engines didn't sound normal this prompted the crew to shut both engines down as soon as they had vacated Runway now the aircraft was taken offline for a full inspection and when the engine's hmus were examined they were found to be filled with cathon slime which made the movements of the valves and pistons much harder than normal one component had actually snapped from The increased torque that the contamination had caused this cathode contamination was found to be the reason behind all of the engine issues that both Crews had experienced this incident led to better guidance regarding on how this type of microbiological treatment should be performed as well as better tooling for mixing the fluids and given the fact that an incorrectly handled treatment could result in the loss of all engines effectively bypassing the multi-engine redundancy of the aircraft the procedure also needed to be classified as safety critical this meant that procedures of this kind had to be monitored by at least two different qualified engineers and all amounts of fuel additive needed to be cross-checked before they were added to the fuel the computer systems used by Engineers to troubleshoot issues also needed to become more error-proof and the training on how Engineers were using these systems needed to be updated but the really big takeaway that I want you guys to really take away from this video is the importance of a well-functioning air crew these Pilots did almost everything right they informed everyone they applied all applicable procedures and kept everyone in the loop even though the external errors in this case kept making the situation worse their good training excellent CRM and airmanship still saved the day I know that sometimes my accident and incident series might give the impression that pilot error and external threats are everywhere but the truth is that there are hundreds of thousands of flights being flown safely by a Crews like this every single day even during really hard conditions like this one and the reason that you don't hear anything about those flights is because of the Fantastic work that my pilot colleagues cabin crew ground crew and everyone else are doing every single day to keep this wonderful industry as safe as it actually is now check out this video next door binge on this playlist I hope that I've earned a subscription from you and if you want to support the work that I do then join my patreon crew or buy yourself some merch have an absolutely fantastic day and I'll see you next time bye foreign [Music]

Channel: Mentour Pilot

Views: 1,615,480

Keywords: Boeing a321, gatwick, standsted, aviation fuel, fuel, contaminated, kathon, serious, london, united kingdom, storytelling, true crime, full episodes, investigation, documentary, entertainment, mentour pilot, mentour now

Id: E4Qclymu2EA

Length: 29min 3sec (1743 seconds)

Published: Sat Dec 24 2022