Having not experienced one (yet) what are the symptoms when it fails?

One or two BUSTIE OPEN captions. Having shut down, the associated engine won't turn over, various red lights when pressing the test button on the EMB. Oh yes, and we've found the info re battery on first.

At least three master boxes, that I know of, on our 2 EC135T1s in 18 months. Symptoms as described above, although we have a separate continuing saga concerning a possible short with the cockpit vent fan. We also connect GPU after BATT ON, although we also found that taking the engines to FLIGHT, switching the BATT MASTER 'off' and then switching 'on' vent, sandfilters and aircon also helped avoid the spike which trips the busties.

Head Turner, interesting that you say there's no mention of minimum voltage for starting. I'm not at work right now, but one of our engineers said the same thing. I showed him the relevant section in the FLM stating min voltage = 24.0, but cannot give you chapter and verse 'til I have the book in front of me.

National Air Support Forum? You are joking, aren't you? I applied through our company head of training way back last year - they never had the courtesy to reply. Shame really - we do virtually nothing but training on these cabs, so we learn a great deal about the aircraft every day. So do Eurocopter - these airframes operate in difficult conditions for helis, and the 135 has its faults like any other design. It'd be a pleasure to share the knowledge - and to learn what people who do a real job get up to - but we can't do any more than ask, can we?

Yes, we've been down that road, but still getting the problem.

Thud and Blunder, I would appreciate knowing where this gem of info is hidden within the FLM. I was told during training that 24V was the limit, but I want to find it in the FLM.

With reference to the minimum voltage...it is referred to on page N-15 of the Pilots Checklist and on page 4-10 of FLM....just for the record. But can't find any info regarding use of GPU.

ECD Service alert 2004-09-22 which contains Thales service letter 4502/3-300/350-24-003. If you're registered for TIPI do a search on "master" and it's the first return :)

EC135 Max TOT Limitations
 

When flying AEO (both engines) the TOT limitation for Max Continuous is 879C (Arrius 2B2), however in OEI conditions the TOT Max Continuous is 942C.
Why is there a difference in the TOT limit?

Head,

Few limits are set at the level where the item blows up if exceeded by 1 degree or 1 percent. Most limits are based on the assumed number of times they are reached, and the number of hours they are flown. That way, a continuous limit for dual engine is lower than the continuous limit for single engine, since dual engine limits are met exch day, but a real engine failure only occurs rarely, so that higher OEI limit is only actually experienced a few times in the engine's life.

The concept of how limits are set, tested and flown is one of the deep mysteries that needs better explanation, by far. In effect, the user (you) the manufacturer (me) and the regulators (the FAA/JAA) are all in a mutual dance, where the limits define the capabilities of the system as tested to the capabilities as approved. Along with this certification system is a means to assure the aircraft is used in agreement with the tested values (limits marking and training and interlocks) and inspected to assure continued safety (HUMS, data recorders and maintenance manual inspections.) The object of this dance is predictable safe operation.

Want to be confused? One type engine can have 4 different sets of limits, and therefore four different dash numbers, even though the parts are all identical. Each new dash number engine can have different power and different overhaul times. It is possible that the same engine can have different power in different countries (due to different ways to interpret the test data.)

Life was simpler when the rules were simple, but those simple rules were never more accurate, frankly.

Nick, do overhaul times follow the different sets of limits ??

eg. country 'a' has a higher limit for eng temp than country 'b'

does country 'a' have a shorter time to overhaul ??


if so, is it a question of trade-offs for TTO vs max temp ??

Is this just a T1 problem or T2 aswell?

Only had the problem since we went T2. No idea if it's linked.

407,
Exactly, the different power/temp ratings carry different lives, with the higher power leading to shorter lives, generally, but not always.

The method of calculating the life is an art, and each agency has a spin on that art. For example, if the exact same engine is tested to US Navy requirements it will have a given power for its overhaul life. If it is tested to FAA/JAA requirements it will have almost 10% more power for the same life. Why? Because the test sequence for the Navy has many more presumed cycles at high power than does the FAA sequence so the Navy engine has to go to its high power often enough to require that power to be less than the FAA will allow, if full life is to be achieved. We call the sequence the "spectrum" and it is the biggest driver for the determination of power and life.

The funny thing is that we now have the tools to measure exactly what the engine truly experiences, so we don't have to guess at a "spectrum" any more, we just have to measure the real life experience, and dock the remaining life accordingly - except that regulatory agencies have no idea how to deal with this new technology, so they just ignore it (so far.)

Sounds like them thar beans again!

Cyclicrik: Good Q...I havent heard of a T1 failing?

Must be same electrics box / looming though (in the airframe)?

We have had both replaced in our T1 in the last 18 months.

The 'spectrum' selected therefore requires a great deal of cristal ball gestimations to make assumptions on aspects such as (a) how many times single engine temp limits will be used, (b) how many exceedencies occur when both engines are operating etc.
On the Eurocopter range of twins there is a recording of all flight criterior. Does this not provide the data for lifing the engine components?

sounds like the real life experience of the engine (and probably other parts of the drive train) is a tool the operators could use :8

you want light corporate tranfer - X $/hr, you want hot and heavy slinging - Y $/hr, as the latter eats into your TTO faster

can't really see it happening though :O

I'll raise it at the User Gp meeting next week.

So it is accepted that the battery should be physically connected prior to plugging the GPU in, but where does it state that the internal power should be switched on?