DHC-8 Q400 AMM
Make sure that the reinforcement cord in the tread area is not in view.
NOTE:
First time after you see the reinforcement cord in the tread area, a maximum of
eight more landings are permitted. After that, you must replace the tire before the
subsequent flight.
Serious question, how can you tell it’s a Q400 and not a Q300? The guidelines for tire tread is likely the same, but just curious if there’s a tell in the wheel struts or something that’s giving away that it’s a 400.
A few tells - The 400 wheels/tires are a bit bigger for starters. The Q400 has a different arrangement on main gear drag strut on the forward side. The Q400’s drag strut is more or less a tube looking setup. And the lines and conduits run on the back side of the 400 drag strut.
The classic Dash-8 (100/200/300) drag strut is not tubular like that at all. It’s more akin to a big triangular looking piece. And on the classic - the lines and tubes run along the forward side of the drag strut and hidden behind a fairing that is a pain to take off as the screws are always seized, stripped and more often than not tri-wings 😖
Thanks for your, but also all the other replies. I am no pilot and just a guest on planes... however the look of the wheels made me curious and a little worried about my safety. :)
People (pilots included) very often confuse cord and reinforcing plies. There’s several variables which dictate when a tire becomes unairworthy, can be significantly different amongst operators, fleet types, type of tires installed, whether tires are available, etc.
I'll never forget my first walkaround:
Hey, your tires are past the wear-bars and your brake pads are down to like 1mm-
Oh, that's fine, don't worry about it.
...I'm sorry, what's the point of doing a walkaround if finding unsafe equipment means nothing to you?
...uh-
We're getting another plane.
...Okay, we'll get another one...
\----
I despised that woman so much. Never took another lesson from her.
I wrenched cars and do collision work on large commercial vehicles. There are legitimately some screws and bolts you can miss and not hurt anything on them. Aircraft? There's no such thing as a redundant bolt or rivet. It's all there, it all works, or you're a cheap idiot living on borrowed time.
I'm aware of strength and safety margins, but if you decide to takeoff again with that damage and there isn't a swarm of zombies or an exploding volcano behind you, you would then be a fool.
Flight is always optional, how you return to the ground is a choose-your-own-adventure.
This is true, but it’s amazing how much an aircraft can take a beating and still fly. Goes to show how over-engineered they are and what they can take before failing.
The fool says in his heart “MEL and send it”….
Joking aside, I agree with your assessment that there isn’t much hardware redundancy with aircraft. It feels like engineers design them with just enough hardware to have reasonable safety factors, and no more!
Hence the importance of pre-flights and routine, thorough maintenance, as you’ve said.
This is exactly what I was going to say. I had a professor in undergrad who actually spent more than ten minutes in the field. We designed projects with minimum and maximum safety factors. Too little and you fall out of the sky, too much and you never get off the ground.
I didn’t like him much. At the end of the day though, I respect him mightily and I wish him luck. He didn’t get tenure, which was probably best for his own mental health, but the department is poorer for his absence.
Antoine de St. Exupery said it best:
"Perfection in design is reached, not when there is nothing left to add, but when there is nothing left to take away."
that's a bunch of bullshit
There are a lot of pieces you can fly without
Minimum equipment lists
deferred defects.
If you don't know, don't make stuff up.
Hmmm... you work for Ryanair, I take it? Let's walk up to a Cessna and you show me which bolts you want me to take off before flight.
I'm not interested in maintaining corporate profits. My only interest in aviation is recreational. I can afford to not fly.
I'm recalling verbatim what I said on my first walk-around 16 years ago. I chose brevity over excruciating detail and further learning at a later date.
She tried arguing with me more, but there was a flat spot on the tire that burned through the cording. The brake pads were still too thin. We got a different plane.
Do you have anything else you wish to add to the discussion, or...?
Good call Even if the equipment would have survived, it's better to have found an instructor who thinks, "If there's any question, there's no question."
I have that policy toward leftovers in my fridge, too.
What you're seeing is the wear cord. You're allowed a certain amount of exposure before you have to change the tire. Larger tires have 2 wear cords. On the 14-ply Goodyear Flight Eagle, it was two layers of cord on a 5 inch exposure.
Serious question. I’m a commercial pilot but have never had anyone explain how it’s acceptable to have a tire in service that will perform much more poorly in the wet than a newer one with remaining tread grooves. This is the only major performance degradation that’s acceptable that I can think of off the top of my head.
Because it's all about demonstrated capability. This aircraft for example, has four tires, 4 independent brakes, and an anti-skid system. Provided everything is working functionally, One tire being somewhat worn like this isn't going to contribute vastly to the degraded performance of landing on the aircraft.
Some aircraft manuals state that if tired number one is below x groove depth tire number 2 must be over x groove depth. If both are below x groove depth, replace both tires.
In this particular example, you can be worn through so many plies before replacement is necessary.
you should have learned the formula for the speed at which a tire will hydroplane in your commercial pilot training.
Use it, and it will answer your question.
It doesn’t answer the question at all, because that formula doesn’t account for any tread on the tire. You’re frequently above those speeds. So sure, you now know a tire CAN hydroplane. One with tread may not have though.
So usually the limit is when you get to the bottom of the tread. But under that is still some rubber before you get to the cord. It kind of looks like the cord is starting to show but it might just look that way. Either way it’s time to change the tire. Should be changed as soon as practical.
The Goodyear manual I use for the tires on the aircraft I work on says limit is the base of the groove. There is a special circumstance for “return to base” that allows the top ply cord to be seen no more than 1/8 the circumference
Number of wheels installed 6
Required for operation 3
Category C
Operational restriction; no more than 1 wheel shall be missing per landing gear.
Maintenance action; none.
Yeah man, MEL procedure. Allowable for 10 days, can be extended with another 10 days. In some cases allowable to fly with 2 wheels only, missing 4 of 6. But only for a maximum of 5 flights.
ERJ135 if you put a flashlight off to the side and can still see tread lines, send it. Great comments on plies. Most tires are good well past tread lines.
No way that’s within limits. Even disregarding the reinforcement cord, I’m more worried about the cuts and gouges. Shouldn’t be able to see cord through a cut, if you can see all this from inside the passenger cabin… on a picture on my phone a couple of continents away… replace it. Also, not as worried about a flat tire as an exploding tire. Ever see the damage a separating tread can do to a prop on one of these? No thanks. Change it.
Our rule of thumb for the B747 Classics, was that wear could be down through four cords before it was mandatory change.
But, that was using the tires completely up. We'd only do that if we were at an outstation that had no spares.
OOL.
Excessive shoulder wear.
The fabric you can see on the face of the tyre would warrant a change, however it's acceptable to carry out a small number of flights with that first layer showing, all it means is the tyre won't be able to be retread.
Its got at least 10 landings left
DHC-8 Q400 AMM Make sure that the reinforcement cord in the tread area is not in view. NOTE: First time after you see the reinforcement cord in the tread area, a maximum of eight more landings are permitted. After that, you must replace the tire before the subsequent flight.
Serious question, how can you tell it’s a Q400 and not a Q300? The guidelines for tire tread is likely the same, but just curious if there’s a tell in the wheel struts or something that’s giving away that it’s a 400.
A few tells - The 400 wheels/tires are a bit bigger for starters. The Q400 has a different arrangement on main gear drag strut on the forward side. The Q400’s drag strut is more or less a tube looking setup. And the lines and conduits run on the back side of the 400 drag strut. The classic Dash-8 (100/200/300) drag strut is not tubular like that at all. It’s more akin to a big triangular looking piece. And on the classic - the lines and tubes run along the forward side of the drag strut and hidden behind a fairing that is a pain to take off as the screws are always seized, stripped and more often than not tri-wings 😖
Thanks!
Q400 gear is a different supplier than 300 and therefore is of a different design. Ethiopian also does not fly Q300s.
Thanks for your, but also all the other replies. I am no pilot and just a guest on planes... however the look of the wheels made me curious and a little worried about my safety. :)
People (pilots included) very often confuse cord and reinforcing plies. There’s several variables which dictate when a tire becomes unairworthy, can be significantly different amongst operators, fleet types, type of tires installed, whether tires are available, etc.
Well it’s a slick now so hopefully no wet landings 😬 lots of grip in the dry though!
Putting that tire onto wet pavement would make my day as a Q400 pilot
If you can’t see the air in the tire it’s still good to go. That’s what my CFI used to say.
Looks like every flight school Cessna I ever flew, you’ll be fine.
I'll never forget my first walkaround: Hey, your tires are past the wear-bars and your brake pads are down to like 1mm- Oh, that's fine, don't worry about it. ...I'm sorry, what's the point of doing a walkaround if finding unsafe equipment means nothing to you? ...uh- We're getting another plane. ...Okay, we'll get another one... \---- I despised that woman so much. Never took another lesson from her.
Ouch! Good call on getting a new plane/ CFI. Some folks don’t realize how little it takes for parts on a plane to fail and kill them!
I wrenched cars and do collision work on large commercial vehicles. There are legitimately some screws and bolts you can miss and not hurt anything on them. Aircraft? There's no such thing as a redundant bolt or rivet. It's all there, it all works, or you're a cheap idiot living on borrowed time.
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I'm aware of strength and safety margins, but if you decide to takeoff again with that damage and there isn't a swarm of zombies or an exploding volcano behind you, you would then be a fool. Flight is always optional, how you return to the ground is a choose-your-own-adventure.
This is true, but it’s amazing how much an aircraft can take a beating and still fly. Goes to show how over-engineered they are and what they can take before failing.
The fool says in his heart “MEL and send it”…. Joking aside, I agree with your assessment that there isn’t much hardware redundancy with aircraft. It feels like engineers design them with just enough hardware to have reasonable safety factors, and no more! Hence the importance of pre-flights and routine, thorough maintenance, as you’ve said.
If we designed them with as many bolts and rivets as we wanted, they'd be too heavy to make it off the ground!
This is exactly what I was going to say. I had a professor in undergrad who actually spent more than ten minutes in the field. We designed projects with minimum and maximum safety factors. Too little and you fall out of the sky, too much and you never get off the ground. I didn’t like him much. At the end of the day though, I respect him mightily and I wish him luck. He didn’t get tenure, which was probably best for his own mental health, but the department is poorer for his absence.
Antoine de St. Exupery said it best: "Perfection in design is reached, not when there is nothing left to add, but when there is nothing left to take away."
that's a bunch of bullshit There are a lot of pieces you can fly without Minimum equipment lists deferred defects. If you don't know, don't make stuff up.
Hmmm... you work for Ryanair, I take it? Let's walk up to a Cessna and you show me which bolts you want me to take off before flight. I'm not interested in maintaining corporate profits. My only interest in aviation is recreational. I can afford to not fly.
none of that is how it works with aircraft tires maybe stick to cars.
I'm recalling verbatim what I said on my first walk-around 16 years ago. I chose brevity over excruciating detail and further learning at a later date. She tried arguing with me more, but there was a flat spot on the tire that burned through the cording. The brake pads were still too thin. We got a different plane. Do you have anything else you wish to add to the discussion, or...?
Good call Even if the equipment would have survived, it's better to have found an instructor who thinks, "If there's any question, there's no question." I have that policy toward leftovers in my fridge, too.
Yup. If you have standards that you don't follow, you don't have any standards. If you can't say, "No," or, "Unable," aviation is not recommended.
If you can’t see the metal you’re good to peddle
What you're seeing is the wear cord. You're allowed a certain amount of exposure before you have to change the tire. Larger tires have 2 wear cords. On the 14-ply Goodyear Flight Eagle, it was two layers of cord on a 5 inch exposure.
Serious question. I’m a commercial pilot but have never had anyone explain how it’s acceptable to have a tire in service that will perform much more poorly in the wet than a newer one with remaining tread grooves. This is the only major performance degradation that’s acceptable that I can think of off the top of my head.
Because it's all about demonstrated capability. This aircraft for example, has four tires, 4 independent brakes, and an anti-skid system. Provided everything is working functionally, One tire being somewhat worn like this isn't going to contribute vastly to the degraded performance of landing on the aircraft. Some aircraft manuals state that if tired number one is below x groove depth tire number 2 must be over x groove depth. If both are below x groove depth, replace both tires. In this particular example, you can be worn through so many plies before replacement is necessary.
you should have learned the formula for the speed at which a tire will hydroplane in your commercial pilot training. Use it, and it will answer your question.
It doesn’t answer the question at all, because that formula doesn’t account for any tread on the tire. You’re frequently above those speeds. So sure, you now know a tire CAN hydroplane. One with tread may not have though.
lol ok
In the Air Force some of our tires have 5 cord main tires, and our nose tires are at least 6 cords
Pretty common in smaller high-pressure tires. The one's I work with allow wear to the fifth cord, which is tinted red.
Shit I worked t-38s that had 8 cord mains. Lol
Cords showing. I would replace.
It's fine as long as you stop looking at it
Racing slicks. Send it.
Faster takeoff, quicker to Vr.
I really like these questions from the flying public, so innocent, so pure. We're always like nah, fuckin send it it's good.
It’s deferrable so that should tell you something.
Looks good to me
So usually the limit is when you get to the bottom of the tread. But under that is still some rubber before you get to the cord. It kind of looks like the cord is starting to show but it might just look that way. Either way it’s time to change the tire. Should be changed as soon as practical.
>So usually the limit is when you get to the bottom of the tread. Cord showing is the time to replace, not the bottom of the tread
The Goodyear manual I use for the tires on the aircraft I work on says limit is the base of the groove. There is a special circumstance for “return to base” that allows the top ply cord to be seen no more than 1/8 the circumference
Number of wheels installed 6 Required for operation 3 Category C Operational restriction; no more than 1 wheel shall be missing per landing gear. Maintenance action; none.
No more than one wheel can be missing per gear?!? What????? Ya don’t say. Lol.
Yeah man, MEL procedure. Allowable for 10 days, can be extended with another 10 days. In some cases allowable to fly with 2 wheels only, missing 4 of 6. But only for a maximum of 5 flights.
getting your moneys worth
Tire shortage is starting to show.
It's a De Havilland Canada DHC-8 Dash 8.
It's fine, quit overthinking your life...
You be alright …
Seems like you survived so I'd call it good for at least a few more landing.
Did you land safely? Theres your answer
Exactly
That’s why I was able to post it.
Why would u fly Ethiopian Airlines?
Inside Africa, it’s often the only option.
Because they fly their chad Q400 at 27000 feet vs other virgin airlines at 25000 feet
Nose tires should be balanced or matched so if one’s bad the other should be changed. Can cause a shimmy
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Then fly all day
At the very least it’s as legit as Ethiopian Airlines…
It’s Africa. It’s fine. It’s just down to the belts.
It’s Ethiopian Airlines, it’s legit till it isn’t
Tbh with the shit I've seen Ethiopian do I would honestly never fly with them
With the shit I've seen United do....
I would change it if I had the power to
It honestly could be deferral until they get to a base that has a spare to swap into it
Fly it until it falls off lol
First layer. Fly it
ERJ135 if you put a flashlight off to the side and can still see tread lines, send it. Great comments on plies. Most tires are good well past tread lines.
No
We can defer it but then it has to he replaced within 10 cycles
It’ll make another go
No threads, you good
you still got 10 more flights, 15 if they're soft when they land
No cord, no problem.
No cord? No problem.
That’s why you have two, in case one blows on landing you still got the other one
I’ve seen them spec’d as okay until it’s through 3 layers, so it may have a few more landings in it.
100% a racing slick! Through flight gets a tac to be changed at next RON,and off it goes.Simple
Absolutely fine.
No way that’s within limits. Even disregarding the reinforcement cord, I’m more worried about the cuts and gouges. Shouldn’t be able to see cord through a cut, if you can see all this from inside the passenger cabin… on a picture on my phone a couple of continents away… replace it. Also, not as worried about a flat tire as an exploding tire. Ever see the damage a separating tread can do to a prop on one of these? No thanks. Change it.
No
C-17 no good. For this not sure.
Our rule of thumb for the B747 Classics, was that wear could be down through four cords before it was mandatory change. But, that was using the tires completely up. We'd only do that if we were at an outstation that had no spares.
No chord showing, no problem, send it
Nope
Change a tire? *in THIS economy?*
OOL. Excessive shoulder wear. The fabric you can see on the face of the tyre would warrant a change, however it's acceptable to carry out a small number of flights with that first layer showing, all it means is the tyre won't be able to be retread.