Seeing the excitement about A2A being able to bring their suite of faults to MSFS, I’m wondering what an accurate frequency of faults might be. 
 

I get that it depends on an awful lot of things, but if you’re sticking to your maintenance regimes, just how frequent are faults, hydraulic, electrical, or emotional😅?

In gliders, mostly emotional :-)

Depends on the level of care the aircraft received.

I posted a topic about this some months ago. For some reason i've had quite bad luck. 😂

My last 50 or so flights (incl attempted flights), 6-7 had some faults to a degree. Everything from dead battery, bad alternator, malfunctioning transponder, collapsed gear strut & flat tire observed upon the daily inspection, red flag on turn & slip indicator, dead light bulbs on some external lights (for night flying they cant be inop)

The planes  are serviced at 50hr & 100hr intervals and logs around 350 hrs flight time annually I believe.

 

 

Depends on the epoch and airframe, too.  In the early-mid 1950s, the MTBF of a generator on a radial engine was in the neighborhood of 40 hours, as an example.

If your GA airplane is a club airplane maintained with approximately the same amount of care as the average lawn mower, and flown by renters with Christmas hams for hands, you might expect a lot of..."issues."

 

30 minutes ago, w6kd said:

 

If your GA airplane is a club airplane maintained with approximately the same amount of care as the average lawn mower, and flown by renters with Christmas hams for hands, you might expect a lot of..."issues."

 

Isn't that lawnmower checked at least once every few years? 

 

1 hour ago, SAS443 said:

My last 50 or so flights (incl attempted flights), 6-7 had some faults to a degree.

That sounds fairly frequent, although not totally unlike the frequency of faults I experienced driving a second (third?) hand Fiat 127 in the early 1990s. I guess the physical forces a plane is exposed to and the rigour with which they're checked mean faults will be found fairly frequently.

Interesting question. I would have to categorize them between show stoppers, minor and nuisance faults. It's a little hard to summarize if you are flying a fleet of aircraft. This is from a jet perspective. The most common nuisance faults are ones such as a VHF radio has more static than normal, a problem with squelch or maybe the side tone isn't working. Now you have to listen carefully to hear on that radio or you can't hear yourself when you are talking on interphone or transmitting on the radio. That side tone sucks because when you can't hear yourself, you start to wonder are you even transmitting out. Another common one would be that you get a left tank fault on the fuel service panel such LT TNK 1 L1. Basically telling you that the specified fuel probe is having some issues. You might even see the left tank quantity flux or bounce around 100 to 300 pounds. Usually it's caused by some water in the tank. Another common one would be some burned out bulbs making a indicator appear dim in the day light. Some nuisance problems you might not even bother writing up if its intermittent. I may go out on a day and have nothing or return from a 7 day trip and have 5 nuisance writ ups.

Minor faults would be those that are a little bit more than a nuisance. FGC1 or 2 is a common one(flight guidance computer 1 or 2). You might get it on the ground or maybe while cruising. If it's bad enough, the AP may kick off, which has never happened to me. Usually when you dig into it under the maintenance page, you will see elevator servo position. It means that the servo is not reporting it's position back to the FGC. On the flight controls page, you might have a blue x on that elevator because it's position is not being reported. In that case, the FGC is controlling it, but the rheostat on it is not reporting back when it's moved. Jet flies fine, but you can't tell the position. Now, during the flight controls check, someone needs to verify it went to those full positions. You can reset the FGC breakers to see if it comes back or just hard select the good one to prevent it from automatically switching after each landing. Another minor we see from time to time is that you go to start an engine and it does not light off. You stop the start, do a motor cycle to clear the fuel and then you attempt another start and it fires right up. In that case, you have a failed channel on that engine so your start will fail every 4th attempt. If so, I track the starts and cycle the switch before the 4th to skip that cycle. These type of faults, you can keep pushing, but have to consider what you are doing. Like if my APU is down, I will press, but will not do any of those 180 minutes from divert routes. I can easily go up to a year or more without one of these, but that's just me. I might not get one of these, but the person flying that same jet tomorrow might.

Show stoppers are the serious ones that may keep you from dispatching. Generator or transformer rectifier failures. shattered windscreen, emergency system failure, gear indicating/retracting problems, anti ice system failure, flight controls, major hydro/fuel leaks, etc. Those are the big ones. I have been flying Gulfstreams since 2007 and have only had two show stoppers that prevented me from departing. I had both VHF radios fail while in Paris. Had to call for the mechanics to come fix us. Ended up being the hand mic jack on the yoke that prevented both radios from transmitting and receiving. The other was a converter failure on the G3. It takes wild AC from the generator and clean it up to stable DC and then converts some back to stable AC. Started the engines, hit the power switch for the right generator and nothing happened. Generator was good, but the converter was toast. I did have a GV windscreen shatter, but we were on the leg home anyway, so it didn't prevent us from dispatching. As most have said, it comes down to how good you take care of them Mx wise. You let things slip and you run into more compounding minors and show stoppers. In my case, it's a testament to the redundancy in aircraft design as well. For example, that engine example I gave or the FGC. If FGC1 is actually toast, then we will keep it on 2 for the remainder of the trip. The G550, being the flying computer it is, had a lot of spurious messages you would get when it first rolled out. Many times I would get a big red X on the PFD and just power it down and bring it back up and it was gone. It was common to be on taxi out and get some CAS message or two pop up. You would tell ground you needed to stop for a couple of minutes. You pull to the side, kill all of the generators and power and then turn it all back on. Those messages would be gone and you will continue to taxi. Things got better after a few software updates. I also remember when we received our first one, we would get baggage fire warnings on takeoff when the FAs left the overhead baggage light on. The fire detection was so sensitive it would set off a fire warning. Good times for sure.

 

6 hours ago, G550flyer said:

Good times for sure.

Really interesting post, thanks for sharing. A real eye-opener as to some of the things pilots need to be able to troubleshoot that most of us simply don’t realize, and also how many safety systems are built into planes nowadays.

Luckily for an airliner point of view things mainly seem to go wrong with the aircraft when its on the ground between rotations, so your biggest headache is working out if and how you can dispatch and what the implications are.

Sometimes things aren’t black and white and require a bit of lateral thinking about the fault and its interaction either with other faults or the operation. An example I can think of is when I was presented with a 747 which had a fault with it’s fuel jettison system. There was no written reason that the aircraft couldn’t be dispatched however on this particular occasion we were flying to a location that had a fuel shortage and so we were tankering fuel, that is taking as much extra fuel as possible on the outbound leg to hopefully go a long way to covering the return sector as well.

I’ll let you have a think yourself what the issues could have been on that occasion.

Other sorts of things I’ve seen while jumpseating on other airlines was a centre rad alt fail on a 747 inflight, not usually an issue but on this occasion the destination was in low viz ops and the aircraft then didn’t have the required autoland status so it resulted in a diversion.

Out of Singapore a hydraulic demand pump failed on taxi out, this would result in reduced speed of gear retraction which then caused a WAT (weight , altitude, temperature) limit which was below the take off weight so the flight returned to stand and was subsequently cancelled.

  

 

On 11/18/2021 at 5:44 AM, jon b said:

Luckily for an airliner point of view things mainly seem to go wrong with the aircraft when its on the ground between rotations, so your biggest headache is working out if and how you can dispatch and what the implications are.

100%. I have a couple of great examples. These examples will demonstrate the consideration that have to be made in regard to the aircraft's issue and the flight.

In the first scenario, it was during the war and I was flying a DC10 to a track in Northern Afghanistan. Once we were ready to get clearance and press, the right AC pack overheated and failed on us. We called the mechanics and they looked over the right pack and decided that the right expansion turbine needed to be changed. I asked for another jet and they said they did not have one ready to go at the time. We elected not to take the jet and the mechanics were furious. One guy got a bit mouthy and I kicked him off of the jet. I get it, it's hot with long hours and they don't have all the resources that they have back at home base. The Mx officer came up and inquired on why we wouldn't take the jet. Their stance was that the MEL or military equivalent said that the jet could dispatch with one AC pack. I then explained that I was going to hang out in an area where the mountains are in the 25,000ft range. If I were to lose that left pack, I also lose pressurization. My response is to get the jet down to 15,000ft or below, preferably 10,000ft. In that scenario, I wouldn't be able to get down to 10,00ft, let alone 15,000ft for a while. We would have to suck the O2 masks for a while with the uncontrollable oxygen flowing into the cabin from the drop masks. I wouldn't want to be droning along at 10,000ft in the AOR full of gas with an oxygen rich environment. There was plenty of gas in the air and they didn't need us. If they needed us, that's when you play the risk management game and get the mission done.

The second scenario happened to be in the same environment, but it was a track in Iraq. That afternoon we were preflighting and both GPSs would not come up. We called out Mx and they took a look. The GPSs are embedded inside of the FMS. They grabbed another FMS from another jet and that one would not come up either. They stated that possibly both GPS antennas were toast. As you can imagine, the desert environment can be rough on an aircraft with the extreme temps and sand. I would arrive to an aircraft and see mechanics sweeping sand out of the intakes of engines 1 and 3. You get a lot of system overheats and weird issues when operating in those types of environments. Unfortunately, I had to turn that jet down and swap to another.

The jet flies fine without GPSs, but INS systems have their inherent drift problem. In that jet, you couldn't use the two GPSs as a navigation source. The system used the GPSs and the three INSs to calculate a NAV solution. As long as the INSs were in NAV mode for at least 30 minutes, the system would use the GPSs to calculate the drift rate of each INS. After 30 minutes, the system could give you a very accurate NAV solution. Even if you lost both GPSs after 30 minutes, you can fly for 19 hours accurately since it knew exactly where each INS would be in that time. The problem in this scenario is that the GPSs were toast from the start so that the Kalmen filter could not calculate the drift rate and NAV solution. It would rely solely on INS position. It's fine, I flew C141s that way. Crossing the pond, you would see airliners off to your right. Your instruments would show you on track. You would compare your track against the airliners to figure out which INS was more accurate and couple to that one. If everything hits the fan, you just follow the airliners lol. Once you were close to a NAV radio, you would update your INS positions and coast into Europe accurately. The DC10s we flew were so accurate that you would fly over another jet by a thousand feet and both RADAR altimeters would momentarily pop to 1000 and back off.

So, in the scenario, entry into Iraq was a small corridor between hostile airspace. You had to be on the money going in and out. You would be in for hours before coming back out. I believe the limit for INS drift was no more than 3 miles drift in an 8 hour period or no more than 3 kts per hour of ground speed while sitting still. You checked it after every flight to ensure they were within limits. Even with a 3 mile drift, that means it's very likely you are in hostile airspace. I highly doubt that someone would have shot at us, but I'm not one for testing theories.    

Those are just some examples of things you may have to consider when you dispatch using the MEL. It could be something as simple as the ADF radio being inop, but what if the only instrument approach is a NDB. Is the ADF radio worth getting fixed or do you take the risk of diverting. It can get interesting outside of airline ops.

Edited November 19, 20214 yr by G550flyer
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See, this is why I love the avsim forums , pilots who also are aware of the merits and enjoyment of  the flight sim hobby are a much nicer well rounded breed I find.

There’s some great lessons to be had reading here about these  stories and experiences from real world pilots.

In comparison if such stories were posted on a real world pilots forum (which I don’t frequent personally, for the following reasons ) then in no time at all there would be someone posting , ah no , what you should have done was this , I know better, you were wrong.

That would be closely followed by a 3rd post saying , no you’re both wrong , I know better than both of you, you should have done it this way. And so it would go on, believe me it’s worse that what is better, MSFS, XP or P3D you get here.

Rick, it’s interesting that you also get pressure from engineering in the military. With the U/S fuel dump system example I gave above I remember getting some serious abuse from engineering management over refusing the jet, the actual line engineers were fine but the management really pushed it. At the time I was a very young captain, for the 747 at least so I think they thought I could be pressured into accepting the jet.

Re crossing the pond, I remember the days before GPS was retrofitted to the 74s and you’d reach the west coast of Ireland and the FMC would get its first DME/DME input and realise it wasn’t quite where the IRS thought it was and the plane would slide off to rejoin the track.

 

23 hours ago, jon b said:

Rick, it’s interesting that you also get pressure from engineering in the military. With the U/S fuel dump system example I gave above I remember getting some serious abuse from engineering management over refusing the jet, the actual line engineers were fine but the management really pushed it. At the time I was a very young captain, for the 747 at least so I think they thought I could be pressured into accepting the jet.

We had this weird rivalry of Ops vs Mx going on in the Air Force. It stems from status reporting. At the base level, departures and cancellations were tracked and pushed up to a higher level for metrics. Everyone would take credit for on time departures, but if there was a delay or cancellation, no one wanted part of it lol. The Ops and Mx bosses would meet regularly with the wing king and those stats would be briefed before they were passed to the next level. Neither of the bosses wanted to be responsible and answer questions about delays and cancellations from the wing king. I guess through the years, this attitude trickled down to the crews and Mx teams. Here's a typical example of how this game played out.

I had another Friday night flyers club flight, which we refereed to as local training missions. Just another boring night of running up and down the AR track for air refueling proficiency.....on a Friday night. When I arrived to the jet, it was full of Mx guys. When I entered, the line supervisor asked, "are you guys going to cancel the local?". I responded, what's up? They said that the she had taken a bird strike on the pilot's front window and that the number 2 needed inspection to see if anything went down the core. Unfortunately, the winds were out of limit for using the JLG lift and harness to do the inspection. I replied, well, if the winds are preventing you from doing the job, you guys should cancel it. They refused. I told them that the winds were forecasted to get worst through out the night. We did our preflight and then grabbed a seat with them to trash talk and share war stories. We had these two rules that governed flights and our situation. First rule was at expected alert time, the crew had to be alerted or left to burn. If alerted, you show up and the duty day starts. If left to burn in crew rest, they could keep you in that state up to four hours past your scheduled departure time. Once four hours hit, they had to alert you or put you back into crew rest for a reset. The second rule was if you were alerted, had you not departed by fours past your scheduled departure time, the crew could elect to reset and go back in crew rest. It protected you from being jerked around while awaiting sliding estimates for a fix. Some times it's best to reset the crew right away to get them out at the earliest time the following day and other times it might be best to burn the crew and maximize their availability if you can get them out after the delay. On this night, it was just a training flight. At four hours past departure, I called it. At least in that case, everyone is good on both sides because you hit a crew management rule. 

At times, they get really antsy about buying a delay or cancellation. Mx tracked your every move. Once you pull up, they radio off, crew show at tail 1799. If you report an issue, they mark the time you reported it. I've had them say, you have been at the aircraft all this time and you are just now reporting the burned out NAV light? Ummm, I just now did the walk around dude. They would fight to the end to hand off the delay to Ops. If you get to the jet late, they would claim that if you were on time, you could have found it early enough to be fixed in time🤣.

Good times!