Thank You To YMMB Tower.

[Sunfish]

Thank you to YMMB Tower this afternoon. I was out doing a few circuits to keep my hand in when all of a sudden I couldn't get rated normal RPM on climb out. Called for a full stop and added that I thought I had a problem "for the record."

YMMB tower re routed traffic for me and got me back down as number one very neatly.

Problem was finger trouble by me as usual. I won't forget that again in a hurry.

[Stationair8]

Did you note it on the M/R, that the PIC seat needs to have brown stain removed?

[Jabawocky]

This thread will be a cracker

Is this time to fess up to a few sins without going to the CASA prison farm?

Let me guess.....forgot the Carby heat was on? Or was it Rich Fine Green

I have posted elsewhere before...ATC are damned good value far more often than they otherwise could be given the workload they have.

J

[VH-XXX]

So you landed and re-threaded the 912 sewing machine?

[The Green Goblin]

At least you avoided a third bent fire wall

You're such an advocate of procedure (looks like your checklist skills are amiss) and how easy us commercial guys have it. Perhaps it's time you admitted to having a healthy respect for the profession rather than your glorified bus driver mentality.

[Sunfish]

Third bent firewall????

Them's fightin words! I've only bent one firewall!

Jaba, the situation arose because of:

1. Finger trouble by me.

2. The last entry on the MR was "engine surging on Left fuel tank" with a "no fault found " sign off.

3. Some time ago I'd had to deal with a busted vernier throttle that made life interesting on the same aircraft.

So my nasty suspicious mind jumped a mile to an (erroneous) conclusion, landed quick smart thanks to a very efficient YMMB Tower, and sorted out what had happened on the ground. For the record, Pornstars have a very effective carb heat, much more pronounced rev drop than Cessna or Piper products.

[Arm out the window]

Is there some problem with declaring a pan?

Obviously a heartbeat-raising moment for you, but if you want priority to get the thing on the ground, that'd be the way to go.

If you didn't declare an emergency, or only 'sort of' did by saying something like "I've got a bit of an engine issue that I'm working on here," you may be doing yourself a disservice. In my experience ATC almost always do a good job of helping us out in emergencies anyway, but why not make it clear-cut and say the magic words that put you unambiguously at the head of the queue?

There was another thread a little while back about a certain Australian airline flight diverting with smoke and fumes which I heard on the airways as it was happening - their words to ATC were to the effect that they were 'ops normal', but with the above-mentioned issues going on. If that's ops normal for those guys, remind me not to book any more flights with them!

I understand there may be company sensitivity about drawing media attention, but if that stops people declaring emergencies then the tail's wagging the dog way too much.

[VH-XXX]

So let me get this straight....

You were doing circuits, you left the carby heat on and you freaked out because it was 100-200 RPM below max takeoff RPM so you almost declared an emergency?

I'd hate to see what happened if something was REALLY wrong.

[Sunfish]

It wasn't 100 -200 rpm mate, it was 800 - 1000 rpm, and boy did it make a difference! The 100 rpm drop you only see when ground testing at less than full power.

[j3pipercub]

So.....what have you learned then Sunfish?

[VH-XXX]

You need to write that up in the MR.

A Rotax 912 does not drop 800-100rpm with carby heat applied under normal circumstances.

Something is wrong with it.

[The Green Goblin]

I think somebody is telling porky pies

Imagine if you were in icing conditions and needed to apply carby heat at a critical moment in flight such as a missed approach?

I doubt any Pilot would find an 800-1000 rpm loss acceptable unless it was due to icing in the carb which was starting to improve quickly with application of heat.

Something tells me that the average GA aircraft with 800-1000 rpm lost would struggle to get airborne let alone fly! (think about 2500 rpm - 800/1000 rpm = 1500/1700 rpm) this is a typical decent power setting for a fixed pitch machine.

Sometimes it's hard to teach someone something when their glass is already full.

[VH-XXX]

The Rotax 912 RPM Max is around 5,800rpm with 5,500 the maximum sustainable rpm. It is certainly possible to happily still fly at 5,000 or much less, however that being said I've never experienced a drop of that many RPM with Carby heat during my several years of 912 personal ownership over 700 hours.

[The Green Goblin]

Sounds like a motorbike to me with rpm like that

[Jabawocky]

GG

Real bikes are only just getting going at those rev's!

[Sunfish]

XXX:

The Rotax 912 RPM Max is around 5,800rpm with 5,500 the maximum sustainable rpm. It is certainly possible to happily still fly at 5,000 or much less, however that being said I've never experienced a drop of that many RPM with Carby heat during my several years of 912 personal ownership over 700 hours.

It was well below 5000 mate (try 4000 - 4200) on climb, then dragged itself up to 5000 on early downwind. Maybe I'd better go have another look. Drains were clear, fuel was sufficient. Electric fuel pump on. Temps and pressures normal. Left tank selected. Could not reproduce it on ground. Engine is a few hundred from needing an overhaul. Mag check OK on ground. I'm assuming it was me - the most fallible part of the system. I normally vary RPM 5000 - 4500 on downwind in the circuit to try and optimise the spacing.

[Phil O'Rupp]

Geez Sunfish, you really do get all the bad luck! Safe flying.