Couple of questions

[jspilot]

I went on a short flight yesterday to a nearby airport but a few things happened which I am seeking answers to.

First, while doing a run up, the engine ran very rough at ant rpm setting between like 1200 and 1400rpm but ran perfectly outside that range. I took extra time on the runups and decided the engine was running well enough for flight and I made it there and back without any trouble. It was really cold yeaterday( below 30 degrees). I suspected maybe a plug issue but not sure. The plane is a c152. Any ideas why this range caused the rough running engine but all other ranges were fine?

Second, while taxing I was asked to change runways for takeoff. The controller originally had me going to a runway that intersected the runway he switched me to. When I completed my taxi, I called for takeoff clearance and was given it. I took the runway to see that I was on yellow chevrons and that indicates you can't takeoff or land and I believe not even taxi on. I continued down the runway at taxi speed until I got out of the yellow chevrons and passed the runway start line. Then I applied takeoff power. I took off and the tower never said anything. Did I handle this correctly? Am I wrong in my understanding that yellow chevrons is a "no go" area?

 

[alfadog]

I cannot speak to the rough idle other than asking if it was leaned. That is because I have no cold-weather experience with aircraft.

As far as the chevrons, if the controller clearly directed you onto them, I would not worry. They (the controllers, not the chevrons) probably only limit heavier aircraft. Ideally, you would have been certain enough in their meaning to query before taxiing onto them but I do not think it was anything to worry about.

 

[timwinters]

Chevrons are indeed a "no traffic" area. No takeoff, landing, or taxi.

I'm surprised the airport has a taxiway leading to such an area though. Seems to be a recipe for producing errors.

 

[jspilot]

Chevrons are indeed a "no traffic" area. No takeoff, landing, or taxi.

I'm surprised the airport has a taxiway leading to such an area though. Seems to be a recipe for producing errors.

This confused me too. I'm going to go in the AFD and see if it is a special marking or something like that. It is a active military airport too although it is not technically an air force base.

 

[FastEddieB]

About the rough running.

I had flown my S FL based Tiger to CT with my family.

On preflight I noticed a little brake fluid in a puddle under the right main. Brakes still felt firm and I wrote it off as cold weather related. It was, and never had that issue again.

But...

Taxiing out, I did notice a little engine roughness. Subtle, but there. Again, wrote it off as cold weather related, and runup and takeoff were normal.

But after leveling off at 6,000' over Long Island Sound, the engine suddenly got very, very rough. Nothing helped. Declared an emergency, headed towards Gabreski (?) field, circled around and landed. On exiting, there was oil all over the nosewheel fairing. I hoped I had not left the oil cap off or something equally stupid, and I hadn't. But opening the cowling revealed a bent pushrod and pushrod tube - which I still have as a souvenir. An exhaust valve had frozen, which caused the rough engine and associated backfiring*.

Lesson? Listen to your engine. Engine failures are usually preceded by some symptom. Lycomings can exhibit "morning sickness" as a prelude to valve problems. The Most Conservative Action is normally to shut down and investigate - very hard to do when you're all primed to go, but it could end up being a life saver someday.

Photo to follow...


*I know - technically after-firing

 

[alfadog]

This confused me too. I'm going to go in the AFD and see if it is a special marking or something like that. It is a active military airport too although it is not technically an air force base.

If the airport sees heavy a/c traffic, part of the runway might be closed to heavier a/c due to a load-bearing issue that would not impact lighter GA a/c. It would still probably be marked with chevrons and the controllers would know what they can put on it. Might be indicated in the airport diagram, but perhaps not. I am speaking as a (retired) civil engineer but not all that familiar with airport design and operation.

 

[Velocity173]

I suspect the rough running engine was due to a little "morning sickness." usually a little carbon on the plugs. Should clear up after the mag check. If not, I wouldn't fly it.

At larger airports (jets) the chevroned area is called the blast pad. The name is exactly its purpose. It's used to absorb jet blast to prevent damage. It's also for aircraft that have overrun the runway. It's not used for taxiing, taking off or landing. There should be a yellow demarcation line indicating the area. While your aircraft isn't going to sink into the blast pad area, generally they aren't constructed with the same load bearing as the runway. Unless the tower has some crazy waiver for light aircraft ops in the blast pad area, you really shouldn't be on it.

 

[poadeleted20]

Second, while taxing I was asked to change runways for takeoff. The controller originally had me going to a runway that intersected the runway he switched me to. When I completed my taxi, I called for takeoff clearance and was given it. I took the runway to see that I was on yellow chevrons and that indicates you can't takeoff or land and I believe not even taxi on. I continued down the runway at taxi speed until I got out of the yellow chevrons and passed the runway start line. Then I applied takeoff power. I took off and the tower never said anything. Did I handle this correctly?

Yes, you did.

Am I wrong in my understanding that yellow chevrons is a "no go" area?

Close -- it's a "no takeoff" area. Whether taxi is allowed or not depends on exactly what they looked like. If the yellow chevrons looked like this:

...then you can taxi on it up to the white threshold line and commence your takeoff from there. However, if the yellow chevrons looked like this:

...then it is a "blast pad". The AIM says "These markings are used to show pavement areas aligned with the runway that are unusable for landing, takeoff, and taxiing," i.e., you are not allowed to taxi on them. For more on this, see the AIM Section 2-3-3.

 

[alfadog]

Yes, you did.

Close -- it's a "no takeoff" area. Whether taxi is allowed or not depends on exactly what they looked like. If the yellow chevrons looked like this:

My read of the OP is that it was the latter, i.e. blast/overrun area.

 

[FastEddieB]

Here's what a Lycoming O-360 may look like after a seized exhaust valve:

The source of the oil was from where the pushrod tube had been hammering against the case.

Fortunately, Mattituck was right nearby and I could do the parts runs in a rented car.

Oh, and after futzing with the repair over two days, the mechanic only wanted to charge me $50. I insisted he take more - I had assumed if I got away with anything under $1,000 I would have been happy!

 

[poadeleted20]

My read of the OP is that it was the latter, i.e. blast/overrun area.

I'll wait for the OP to look at the pictures and tell us which it is. If a blast pad, IIRC, there shouldn't be an open taxiway leading onto it.

 

[alfadog]

I'll wait for the OP to look at the pictures and tell us which it is. If a blast pad, IIRC, there shouldn't be an open taxiway leading onto it.

If the OP is talking KFRG then I can see how he could have entered the no-taxi zone from the through-taxiway to the museum. It would be a screw-up but it could be done.

 

[alfadog]

Here's what a Lycoming O-360 may look like after a seized exhaust valve:

The source of the oil was from where the pushrod tube had been hammering against the case.

Fortunately, Mattituck was right nearby and I could do the parts runs in a rented car.

Oh, and after futzing with the repair over two days, the mechanic only wanted to charge me $50. I insisted he take more - I had assumed if I got away with anything under $1,000 I would have been happy!

Did you just swap out the cylinder?

 

[timwinters]

Ron, your first example don't appear to be Chevrons by the definition that's also contained in the AIM section you reference. They are apparently simply considered "arrows".

Here's what the AIM says:
"1. Chevrons. These markings are used to show pavement areas aligned with the runway that are unusable for landing, takeoff, and taxiing. Chevrons are yellow. (See FIG 2-3-7.)"

Yes, you did.

Close -- it's a "no takeoff" area. Whether taxi is allowed or not depends on exactly what they looked like. If the yellow chevrons looked like this:

...then you can taxi on it up to the white threshold line and commence your takeoff from there. However, if the yellow chevrons looked like this:

...then it is a "blast pad". The AIM says "These markings are used to show pavement areas aligned with the runway that are unusable for landing, takeoff, and taxiing," i.e., you are not allowed to taxi on them. For more on this, see the AIM Section 2-3-3.

 

[FastEddieB]

Did you just swap out the cylinder?

No.

The mechanic just pushed the exhaust valve into the cylinder, reamed out the valve guide, then used fishing line to snag the valve and pull it back through the guide. That was the most tricky/tedious part, IIRC. Replaced the pushrod and tube and seals, obviously.

Cylinder never came off.

Seemed to work - never had issues with that cylinder or others again.

IIRC, there was a "wobble test" that you were supposed to perform, and the engine oil was supposed to have additives either in the oil itself or added to prevent that sort of thing. I think it was the "plus" in Aeroshell Plus, but it was a long time ago.

 

[alfadog]

No.

The mechanic just pushed the exhaust valve into the cylinder, reamed out the valve guide, then used fishing line to snag the valve and pull it back through the guide. That was the most tricky/tedious part, IIRC. Replaced the pushrod and tube and seals, obviously.

Cylinder never came off.

Seemed to work - never had issues with that cylinder or others again.

IIRC, there was a "wobble test" that you were supposed to perform, and the engine oil was supposed to have additives either in the oil itself or added to prevent that sort of thing. I think it was the "plus" in Aeroshell Plus, but it was a long time ago.

Wow, he sure did you a solid for $50, then. The W is Lycoming additive LW 16702 anti-scuffing agent.

 

[poadeleted20]

Ron, your first example don't appear to be Chevrons by the definition that's also contained in the AIM section you reference. They are apparently simply considered "arrows".

AIM definition is one thing; appearance/perception is another. That's why I posted pictures and asked.

 

[jspilot]

Yes, you did.

Close -- it's a "no takeoff" area. Whether taxi is allowed or not depends on exactly what they looked like. If the yellow chevrons looked like this:

if the yellow chevrons looked like this:

...then it is a "blast pad". The AIM says "These markings are used to show pavement areas aligned with the runway that are unusable for landing, takeoff, and taxiing," i.e., you are not allowed to taxi on them. For more on this, see the AIM Section 2-3-3.

The above example is what they looked like. The Airport in question is KFOK( for those who want to look at the taxi diagram. Here is the thing though. Parts of the taxiways were not plowed and I was taxing from the FBO to runway 6. I was originally cleared to taxi to 33 via W and S but got switched to 6 mid taxi. I have a feeling what happened was the taxiway was not cleared well enough for me to turn from W onto 6 and I had to continue straight ahead on W a little bit more into the yellow chevrons because of snow build up. Anyway, it clearly was not a problem because I got no "call this number" so I'm not worried.

Thanks for the tips on the engine. I rent the plane so I'm not in charge of getting things fixed. I let the owner know after the flight and he took a note about it.

 

[poadeleted20]

The above example is what they looked like. The Airport in question is KFOK( for those who want to look at the taxi diagram.

Here it is:

http://155.178.201.160/d-tpp/1402/00996AD.PDF

Here is the thing though. Parts of the taxiways were not plowed and I was taxing from the FBO to runway 6. I was originally cleared to taxi to 33 via W and S but got switched to 6 mid taxi. I have a feeling what happened was the taxiway was not cleared well enough for me to turn from W onto 6 and I had to continue straight ahead on W a little bit more into the yellow chevrons because of snow build up. Anyway, it clearly was not a problem because I got no "call this number" so I'm not worried.

Going from W onto 6 you would at worst be just barely a couple of feet onto the blast pad/overrun. Completing the turn onto the actual runway (i.e., northeast of the runway threshold line) and rolling a couple of feet before adding power for takeoff isn't going to bother anyone, especially if that was necessitated by snow blockages. If tower said nothing, sweat not.

However, in the future, if you are in the situation depicted in the second picture I posted:

...then when you pull onto the runway, just make sure you turn right, not left.

 

[alfadog]

Going from W onto 6 you would at worst be just barely a couple of feet onto the blast pad/overrun. Completing the turn onto the actual runway (i.e., northeast of the runway threshold line) and rolling a couple of feet before adding power for takeoff isn't going to bother anyone, especially if that was necessitated by snow blockages. If tower said nothing, sweat not.

Actually, it looks like everyone that uses RW 6 taxis on the chevrons for the entire length of them. I do not see what other option he had if he was on W and they told him to take 6.

 

[gismo]

Thanks for the tips on the engine. I rent the plane so I'm not in charge of getting things fixed. I let the owner know after the flight and he took a note about it.

It's not clear to me whether or not you got this but when you detect an engine problem (i.e. roughness at part throttle) it's generally not a good idea to take off just because it seems to go away at full throttle unless you are able to eliminate the issue (e.g. clearing a carbon fouled plug by running at high power). Failure to heed this advice can lead to the unpleasant feeling of being in the air wishing you were on the ground.

 

[Velocity173]

That's a crazy looking jet blast pad / overrun area. Chevrons with a yellow X? You can actually see it used to be part of the usable runway with the runway aiming markers faded. It's like an obstacle encroached on the approach path and instead of displacing the threshold, they made an overrun.

I'd call the tower and find out if it's a usable area for flight operations.

 

[RV10flyer]

Read the "older" Foreflight or check FAA notams(NOTAMs or Notices to Airmen...Thanks McFly)

See Google Earth for the latest imagery not Foreflight.

FOK 01/003 (KFOK A0004/14) FOK RWY 6/24 SW 1050FT CLSD EXC TAXIING 1401021924-1404011200EST

Looks like the old runway safety area is closed for ANG taxiway construction.

You did the right thing by taxiing on the chevrons under tower's control and clearance. They just assumed you read the notam. Good questions to keep us on our toes, looking for details and asking why. On your engine issue, I agree with others that mentioned getting it checked. If mine does not run smooth and normal before takeoff, I am taxiing back to find out why. You definitely don't want engine issues with all of that cold water around. Thanks for posting.

 

[Velocity173]

NOTAMs!

 

[jspilot]

The above picture is what it was. I had to taxi on the yellow chevrons the entire way. Great to know I did the right thing by taxiing on the yellow and taking off after that line!

With regards to the engine roughness, I agree that is was probably an issue somewhere. I probably should not have flown. It was a tough call because every other power range was a non-issue. I guess I got my warning and should have heeded it.

 

[LifeInverted]

About the rough running.

I had flown my S FL based Tiger to CT with my family.

On preflight I noticed a little brake fluid in a puddle under the right main. Brakes still felt firm and I wrote it off as cold weather related. It was, and never had that issue again.

But...

Taxiing out, I did notice a little engine roughness. Subtle, but there. Again, wrote it off as cold weather related, and runup and takeoff were normal.

But after leveling off at 6,000' over Long Island Sound, the engine suddenly got very, very rough. Nothing helped. Declared an emergency, headed towards Gabreski (?) field, circled around and landed. On exiting, there was oil all over the nosewheel fairing. I hoped I had not left the oil cap off or something equally stupid, and I hadn't. But opening the cowling revealed a bent pushrod and pushrod tube - which I still have as a souvenir. An exhaust valve had frozen, which caused the rough engine and associated backfiring*.

Lesson? Listen to your engine. Engine failures are usually preceded by some symptom. Lycomings can exhibit "morning sickness" as a prelude to valve problems. The Most Conservative Action is normally to shut down and investigate - very hard to do when you're all primed to go, but it could end up being a life saver someday.

Photo to follow...


*I know - technically after-firing

I'll second this story. Had spent a few years flying multi-engine aircraft and a trip home saw me in a good old C-172 after lots of time out of that airframe. Lots of vibration at low RPM but ran smoothly at higher power settings and I too chocked it up to the weather. Lost a cylinder on takeoff after a few currency touch and goes earlier that afternoon. If something doesn't feel right, it probably isn't. Better be safe than sorry.

 

[poadeleted20]

The above picture is what it was. I had to taxi on the yellow chevrons the entire way. Great to know I did the right thing by taxiing on the yellow and taking off after that line!

Lesson to learn: Next time, get and read all the NOTAM's -- that would have saved you needing to ask this question in the first place.

 

[jspilot]

Lesson to learn: Next time, get and read all the NOTAM's -- that would have saved you needing to ask this question in the first place.

Yes sir. It's amazing how much learning happens every flight! I flew for all of 40 minutes yesterday but what a valuable time!

 

[signu127]

What does "exc" stand for on the notam?

 

[Velocity173]

What does "exc" stand for on the notam?

Except