Caravan Missing Near Nome

[geezer]

The rules in Alaska have always been a bit different, for good reasons.

I was riding right seat in a Navajo, loop passenger and cargo route.
Fairbanks, Central, Circle, Eagle, Fairbanks.

Weather was gorgeous for the 3 legs to Eagle.

Departing Eagle, the mountains on our route were shrouded with clouds, and the Pilot call ATC, and requested IFR to Fairbanks.
The response....Radar is out of service, no IFR is available.

I was not looking forward to snaking through the passes with hazy visibility, but the pilot continued to climb right into the clouds, and soon we were on top.

Scary? Not really, it had dawned on me that every one wishing to fly IFR in our region was on this frequency, and it was silent. There fore, there were no other planes there.

In the region around Fairbanks, there were no clouds, so the arrival there was VFR.

Those mountains were tall enough that they extended through the clouds in several places.

 

[AV8R_87]

We told ATC that we needed to descend but they said no. Something about a restricted area.

That's one instance where I would definitely not take no for an answer. Declare an emergency and deal with it later. Or let them deal with it.
A few years ago a friend and I were IFR in a 172, and we started noticing a bit of ice on the wheels and the struts. First icing encounter for both of us, told ATC we were experiencing light icing and asked for lower, which was instantly granted.

 

[Kent Wien]

Our company’s (Era) ops specs allowed for IFR flight in uncontrolled airspace out of Bethel to the villages in the Twin Otter.

Bering Air is a very respected company with an incredible safety record to date. It’ll be interesting to see what the NTSB comes out with.

 

[JOhnH]

That's one instance where I would definitely not take no for an answer. Declare an emergency and deal with it later. Or let them deal with it.
A few years ago a friend and I were IFR in a 172, and we started noticing a bit of ice on the wheels and the struts. First icing encounter for both of us, told ATC we were experiencing light icing and asked for lower, which was instantly granted.

We certainly considered that, but in the few seconds we had to make a decision we also considered the bureaucratic headaches that would cost later, and also that climbing was a perfectly valid decision. If we were not aware that the cloud layer we were in was not very thick we might have made a different decision.

 

[Zeldman]

we also considered the bureaucratic headaches that would cost later,

What bureaucratic headaches.?? This is the last thing to worry about, especially in icing conditions. ATC is there to help you. I am a little surprised ATC did not ask you if you had something to declare.

I have declared a number of times for different reasons under Pt 135 and only once I had a fed talk to me about it. And all he wanted was the flight number and the reason I declared, then he told me I interrupted his lunch...

I always made it a habit to meet the guys in the crash rescue trucks and thank them for being there even though nothing happened.

 

[Rene]

. . . . We did it with TBMs as well . . .

That would be so awesome!

But . . . how do you make any money with such a small cabin?

 

[DavidWhite]

The rules in Alaska have always been a bit different, for good reasons.

I was riding right seat in a Navajo, loop passenger and cargo route.
Fairbanks, Central, Circle, Eagle, Fairbanks.

Weather was gorgeous for the 3 legs to Eagle.

Departing Eagle, the mountains on our route were shrouded with clouds, and the Pilot call ATC, and requested IFR to Fairbanks.
The response....Radar is out of service, no IFR is available.

I was not looking forward to snaking through the passes with hazy visibility, but the pilot continued to climb right into the clouds, and soon we were on top.

Scary? Not really, it had dawned on me that every one wishing to fly IFR in our region was on this frequency, and it was silent. There fore, there were no other planes there.

In the region around Fairbanks, there were no clouds, so the arrival there was VFR.

Those mountains were tall enough that they extended through the clouds in several places.

It’s hard to hit a mountain if you are above them. I know several pilots who killed themselves worrying about maintaining VFR and staying legal while neglecting the most important rule. “Do Not Crash”

 

[Matthew]

It’s hard to hit a mountain if you are above them. I know several pilots who killed themselves worrying about maintaining VFR and staying legal while neglecting the most important rule. “Do Not Crash”

I was volunteering as a judge assistant at an IAC (aerobatic) contest a long time ago. One of the pilots had an emergency when his Pitts had a control failure. The judge I was working with was that pilot’s aerobatic coach and I handed him my handheld so they could work through the problem. The judge/coach said, “Remember Rule 1(a).”

When the emergency was over I asked about Rule 1(a).

“Rule 1(a): No one ever collided with the sky.”

 

[flyingcheesehead]

That would be so awesome!
View attachment 138135
But . . . how do you make any money with such a small cabin?

Alas, not THAT kind of TBM.

The Tarbes Mooney:

 

[Bill]

Alas, not THAT kind of TBM.

The Tarbes Mooney:

Didn’t know those had an aardvark emulation mode.

 

[flyingcheesehead]

Didn’t know those had an aardvark emulation mode.

Are you referring to the intake scoop that comes forward under the spinner?

If so, that was an improvement that they made on the TBM 900 (and later). For comparison, here's an 850:

Fairly subtle difference visually, and IMO the older one actually looks a little better. However, the difference in function is astounding - The newer intake allows significantly better airflow to the engine, resulting in being able to maintain max torque to a higher altitude as well as no delay in restarting the engine after a shutdown. With the older intake, you need to wait about a half hour with the cowling propped open before the engine is cool enough that you won't cook it when you start it back up.

 

[AV8R_87]

With the older intake, you need to wait about a half hour with the cowling propped open before the engine is cool enough that you won't cook it when you start it back up.

Can't you just motor it to bring the temperature down before adding fuel?

 

[flyingcheesehead]

Can't you just motor it to bring the temperature down before adding fuel?

Depends on OAT, but you can only motor it without starting it once really. After 30 seconds of motoring, you have to wait a minute for a start attempt. If you motor twice, then you need another 5 minutes before a start attempt; after that it's 30 minutes. Of course, after 30 it'll be cool anyway.

What does make a big difference is using a GPU *and* motoring. GPU keeps the voltage high enough that the engine spins up quite a bit faster and moves a lot more air. However, the GPU plug is in a rather unfortunate location (about halfway between the leading edge of the wing and the prop) and there are a lot of FBOs that won't do a GPU on a TBM because of it. I always briefed the linemen to keep a hand on the leading edge of the wing when pulling the plug or I'd shut down, but with that big prop it'd probably still be fatal if they kept going in that direction.

 

[Bell206]

Depends on OAT, but you can only motor it without starting it once really. After 30 seconds of motoring, you have to wait a minute for a start attempt.

Interesting. So the TBM takes more than 30 seconds of motoring to drop the ITT to <150 degrees for a start attempt?

 

[flyingcheesehead]

Interesting. So the TBM takes more than 30 seconds of motoring to drop the ITT to <150 degrees for a start attempt?

Depends on the initial conditions (engine temp and OAT), but you can't motor 30 seconds and then start. You've got about 18-20 seconds to light it up or you'll have to abort the start later in the process anyway, and if you still lit it up all you'll do is make it hotter.

 

[AV8R_87]

Bell206 and I have the same thought on this. Motor for 30 seconds to cool the engine, then wait a minute to cool the starter, then hit the starter again and add fuel.
You can't get it below 150 with 30 seconds of motoring?

 

[flyingcheesehead]

Bell206 and I have the same thought on this. Motor for 30 seconds to cool the engine, then wait a minute to cool the starter, then hit the starter again and add fuel.
You can't get it below 150 with 30 seconds of motoring?

Yes. Motor 30, wait 60, motor 20, light it up should work at least 99% the time... But the 900s, you could light up the first time every time.

 

[Bell206]

Depends on the initial conditions (engine temp and OAT), but you can't motor 30 seconds and then start.

Interesting again. I've performed 1000s of starts during mx runs which were repetitive with a <10 min cycle and dont recall any engine that needed a 30 sec motor to get below 150. Hence my question. Curious why the TBM is so different than other aircraft I've ran?

 

[JOhnH]

I hate to ask stupid questions (but if I didn't I wouldn't be asking many questions), but what do you all mean by "motor"?

 

[Bell206]

I hate to ask stupid questions (but if I didn't I wouldn't be asking many questions), but what do you all mean by "motor"?

To spin the turbine via the starter without initiating a start. Its used for several reasons. Some OEMs call it a Dry Motoring Run:

 

[flyingcheesehead]

Interesting again. I've performed 1000s of starts during mx runs which were repetitive with a <10 min cycle and dont recall any engine that needed a 30 sec motor to get below 150. Hence my question. Curious why the TBM is so different than other aircraft I've ran?

Sorry, I was referring to the "30 in 30" limit. You have to be at 30% Ng within 30 seconds of initiating the start, so you can only motor for about 18-20 seconds before you light it up.

 

[flyingcheesehead]

I hate to ask stupid questions (but if I didn't I wouldn't be asking many questions), but what do you all mean by "motor"?

The only stupid question is the one you didn't ask. And I know that turbines confused the heck out of me before I started flyin' 'em. They're... Different.

To spin the turbine via the starter without initiating a start. Its used for several reasons. Some OEMs call it a Dry Motoring Run:

To expand on this a bit, and flesh out what we're actually referring to in this instance especially:

One of the important limits on a turboprop is the inter-turbine temperature (ITT). This is the temp between the compressor and power turbines, and is one of the things you monitor religiously. Different installations and variants have different limits, but for example, some of the TBMs had a normal limit of 840ºC continuous (we tried to keep it under 800), and during start you could go to 870ºC for 20 seconds or 1000ºC for 5 seconds. This gets really expensive if you make a habit of it, though!

And speaking of which, @Bell206, maybe part of our disconnect is that we didn't use the 1000ºC limit - If it was gonna go over 870 we'd shut it down. So maybe we were just being more conservative.

Anyway, when the engine was just running, it is HOT inside. It's pretty much a controlled fire in the combustion section. And it's kept cool by airflow. When you shut down the engine, the airflow goes away and the engine will get hotter before it starts cooling down.

On startup, even from cold, you need to get that air flowing to get everything moving in the right direction and ensure you don't exceed any temperature limits (a "hot start"). On a normal start, you need to spin the compressor section up to at least 13% before introducing fuel. However, when you're starting an engine that was just recently shut down, it may still have an ITT of several hundred degrees and it'll heat up really quick once you light it up in any case, so if you're starting from a hot ITT you're at a very high risk of a hot start. "Motoring" is just letting the starter spin longer without introducing fuel. In this case, that starts pumping outside air into the engine, which cools it down. Once it hits 150ºC, you can light it up - But if that doesn't happen within 18-20 seconds, you'll miss one of the starter limitations, which is that you must be at least at 30% within 30 seconds of turning the starter on.

Another thing that can happen is a "wet start" where you put fuel into the engine but it doesn't light off for whatever reason (you had the ignition off or your ignitors are bad, maybe). In that case, you'll have fuel inside the engine and if you attempt a start that fuel can light up right away, much earlier than 13%, because under normal conditions the ignitors are on any time the starter is on. If you listen to a turboprop starting, right when the engine just starts to spin, you can hear a "click click click" at maybe 2-3 Hz, that's the ignitors. So, to "dry" the engine out and get rid of that fuel to make a start safe would be another reason for motoring.

Fun stuff to learn about.

 

[Bell206]

maybe part of our disconnect is that we didn't use the 1000ºC limit - If it was gonna go over 870 we'd shut it down. So maybe we were just being more conservative.

Not at all. Using the upper start temp limits would only cause me more work later on and I would castrate any pilot I would catch using those upper limits unless someone was shooting at them. It sounds more like Socata needs to limit the start sequence like other select single PT6 aircraft OEMs. The starter-generator is usually an airframe item so you'll find the same base engine (PT6) with different starter limits as the engine only cares about internal temps. The only other OEM I've seen with a similar issue were the turbine AG Trucks.

 

[flyingcheesehead]

Not at all. Using the upper start temp limits would only cause me more work later on and I would castrate any pilot I would catch using those upper limits unless someone was shooting at them. It sounds more like Socata needs to limit the start sequence like other select single PT6 aircraft OEMs. The starter-generator is usually an airframe item so you'll find the same base engine (PT6) with different starter limits as the engine only cares about internal temps. The only other OEM I've seen with a similar issue were the turbine AG Trucks.

Ah. What do other OEMs' starting limits look like?

 

[flyingcheesehead]

Ah. What do other OEMs' starting limits look like?

Just for the heck of it, I looked into my collection of PIMs.

King Air 90 (2000) starter limits: 40 seconds on, 60 off, 40 on, 60 off, 40 on, 30 minutes off.
Same for the King Air 200 (2004).
PC12 says "Sequence, 60 seconds OFF, Sequence, 60 seconds OFF, Sequence, 30 minutes off."

So they kinda sound similar, but without the 30/30 limit and the TBM gets 20 seconds more than the King Airs to complete the start while Pilatus doesn't have a specific limit.

 

[Bell206]

Ah. What do other OEMs' starting limits look like?

I believe the Ag Trucks were more restrictive than your TBM. Something like one 60 sec motor and 5 min cool down. Was trying balance the prop on one and usually charged a flat rate but had to supplement some time for starter cool down. But ever had problem on King Airs or PT6 powered helicopters or other engine brands. My guess for the variety of starter limits is the airframe electrical system sizing and components. Also a number of FADEC controlled engines/aircraft don't even publish a min TOT/ITT/T4 temp prior to start as the FADEC will motor the engine until it hits the "150" limit then light it off.

 

[flyingcheesehead]

I believe the Ag Trucks were more restrictive than your TBM. Something like one 60 sec motor and 5 min cool down. Was trying balance the prop on one and usually charged a flat rate but had to supplement some time for starter cool down. But ever had problem on King Airs or PT6 powered helicopters or other engine brands. My guess for the variety of starter limits is the airframe electrical system sizing and components. Also a number of FADEC controlled engines/aircraft don't even publish a min TOT/ITT/T4 temp prior to start as the FADEC will motor the engine until it hits the "150" limit then light it off.

Yeah, on the TBM 960 (which has FADEC) the limit is 30 seconds for manual dry motoring, or 80 seconds when operated automatically by the FADEC (which will obey the limit automatically).

 

[Bell206]

Yeah, on the TBM 960 (which has FADEC) the limit is 30 seconds for manual dry motoring, or 80 seconds when operated automatically by the FADEC (which will obey the limit automatically).

And you'll find a number of OEMs will have you abort the start long before 80 sec based on lite off and N1 acceleration. I think the difference between the 30 and 80 sec limits on the same starter is based a legacy procedure where some OEMs did not apply starter limitations during an actual start as the engine acceleration reduced the starter load. At least thats how I recall it to be.

 

[Den60]

I’ve heard they had sleet and freezing rain in the area. Grim outlook but praying just the same.

I wonder if the 208 had TKS or just the factory deicing boots.