Boroscope results

[fruitloop]

Just a quick question as to whether you think that the results from this boroscope should have stopped this engine before any more flights occured..
Fruitloop48's Library | Photobucket (http://s1347.photobucket.com/user/Fruitloop48/library/?sort=3&page=1)
The engine in question is a V2500 and what you can see are the Stage 1 HPT..

[Exup]

What is the point of this question. I do not have a copy of the AMM with the applicable limits and I would like to think that the person doing the boro had the information & made his assessment on that basis. He is the one responsible for the inspection & has to answer for it so why try to second guess him on a public forum.

[lomapaseo]

Typically you do this kind of borescope at a station that experts you to follow the written instructions against your findings.

If you are in a tight spot and need additional ad-hoc advice than I would expect the experts to grant you an OK to fly for X amount of cycles before repair/replace as this doesn't appear to be a sign of imminent failure but rather a wear out mode

[fruitloop]

The reason for asking this question is that the Engineer who did the inspection was "Over-ruled".His results were as per the AMM (10 cycles maximum).I believe another engineer was then asked to do a re-assessment WITH different results........

[orion1210]

If the final results are border line in relation to engine manual limits and therefore open to interpretation, as i assume is the case, the OEM is only a call/email away. They may allow greater limits in some cases with additional time/cycle limits. Whilst an engineer may feel he can make a call on an individual piece of damage such as this he lacks the design knowledge of what other possible defects could arise as a result and in what time scale.

Aside from airsafety implications through ignoring approved damage limits consider financial risks with mortgage/lease companies who expect their engines to be maintained to the letter... This is a given, not just when the worst happens!!

[Mr @ Spotty M]

Was the borescope carried out by a kit that could carry out measurements?
If not, you can not be 100% sure who is correct in there assessment.
As pointed out previously, the OEM is your point of contact if you are uncertain.

[SeldomFixit]

"Risk Management" will win out in the end. If it got home everyone will pat themselves on the back for proving risk management works. If it didn't - cue the guillotine for the bloke that released it who must somehow have misunderstood the clear, concise instructions issued by the risk managers :uhoh:

[kapton]

fruitloop.

As the previous posters have already said, the bible is the AMM limitations. If there is some doubt then the OEM must be contacted for a definitive answer. You are obviously concerned enough to advertise this dilemma on an open forum. What is worrying is that an engineer was over-ruled, even though he appears to be following sound engineering practise. Who was the person putting pressure on another engineer to sign the defect off? Is that person licensed?
On face value this appears that your company has a manager who does not hold current approvals, if at all, and is using a weaker willed engineer to stamp a job off.
It seems that an unqualified person, is exerting pressure by virtue of his position, to impose unsafe work practises. Remember, the person exerting the pressure is not certifying anything, so can sleep easy at night. If anything goes wrong he will walk away without a second thought.
Unfortunately there are too many of these characters in management positions who produce a mean powerpoint presentation, but would get a dose of the vapours if they were sent to a line defect with a plane full of passengers about to depart. If you are concerned enough, contact CASA.

[lomapaseo]

Who was the person putting pressure on another engineer to sign the defect off? Is that person licensed?

whoa ... you're reading too much into this.

I was thinking (imaging) things along the lines that one qualified engineer reviewed the picture findings against a picture ih the AMM and said OK, while the boss said to be sure lets get another opinion who found a different picture in the AMM and said I think it could be this.

Since we don't know the final results it's not fair to suggest otherwise.

all I opinioned was that it was OK to fly a few more flights but otherwise needed to be scheduled for maintenance.

For all I know this might be a beer bet only after the fact

[Jet II]

FWIW - My copy of the AMM states:

2) Remove the engine in less than 10 cycles if:

(a) The nick or dent is in area A or area B and shows signs of torn
metal or cracks.
(b) The nick or dent causes internal areas to show. These are areas
where the air that is used to cool the blade goes.

So I would give it a 10 cycle limit.

[bcgallacher]

I am not familiar with this engine and its borescope limits but it appears to have burn through exposing cooling passages,if the MM states that a ten hour limit should be imposed then there is no option. If the certifying engineer allows himself to be pressured by his superiors then frankly he should take up another profession as he is a dangerous man.

[fruitloop]

Jet 11
That is how i read it..!!!Thank you ..
lomapaseo
No I believe he is NOT licensed...But being in a managerial position dictates..!!
kapton
You have hit the nail on the head..thank you.

[mono]

Well I'm going to offer my tuppence worth.

2) Remove the engine in less than 10 cycles if:

(a) The nick or dent is in area A or area B and shows signs of torn
metal or cracks.
(b) The nick or dent causes internal areas to show. These are areas
where the air that is used to cool the blade goes.


These criteria do not apply here. The damage is not a nick or dent, it's burn-through, and for this type of damage the limits are different. There are different limits for nicks/dents, cracks and erosion/burn-through.

The image looks to me to be showing the trailing edge (difficult to be sure as I can't see the platform), but not in the tip area (classed as 3mm from the tip). therefore for me the following limits apply.

(1) Accept with an inspection each 600 hours if:

(a) The erosion or burn on the leading edge is more than one quarter of the airfoil radial length.

(b) The erosion or burns on the leading edge have changed the airfoil shape.

(c) The erosion or burns on the airfoil or platform have gone through the coating. This does not include burns on the airfoil leading edge, trailing edge, or tip.

(d) The erosion or burns on the trailing edge in the inner 25 percent span are more than 0.07 in. (1.78 mm) and less than 0.11 in. (2.79 mm) axially.

(e) The erosion or burns on the trailing edge beyond the inner 25 percent span are more than 0.12 in. (3.05 mm) and less than 0.20 in. (5.08 mm) axially. This does not include the blade tip.

(f) The burning at the blade tip in zone 1 is at the bottom of the lower tip cooling row holes.

(g) The burning at the remainder of the tip (but not including the trailing edge tip) is more than 0.06 in. (1.52 mm) radially and above the top edge of the upper cooling holes.

(h) There is material that is burned away or missing on the blade trailing edge tip that is more than 0.07 in. (1.78 mm) axially from the trailing edge.

(i) The leading edge burn-through beyond the 50 percent span is less than 0.08 in. (2.03 mm) axially and 0.20 in. (5.08 mm) radially.

NOTE: The blade trailing edge tip is 0.15 in. (3.81 mm) radially from the tip and 0.10 in. (2.54 mm) from the trailing edge and burning or erosion is permitted in this area.

From this I feel the damage fits the limit in para (e) and would release with a 600hr re-inspection.

Of course, as has been said. Any doubt it's easy to contact IAE to get a definative response.

[Jet II]

mono - I think you need to reassess.

The damage is on the L/E, and to me it is typical impact damage for 1st stage HPT. Even it it were burn-through (and I'm struggling to see the evidence of burning), your reference does not apply under para 'C' "This does not include burns on the airfoil leading edge, trailing edge, or tip."

I would make it clear that I am using the AMM for a different operator - the AMM that the individual case used may be different (although I would not expect the limits to have changed)

[lomapaseo]

I thought it was a burn through but I will retire against any photo examples against this in the AMM which is really the juxt of my earlier response and not an arm-chair judgement via Pprune :)

The kt factor is different although a location near the tip mitigates the effect

[mono]

Well if you say it's the LE then I bow to your superior knowledge.

I think you're misreading para (c) though. It doesn't include burns on the LE, TE or tip as they're dealt with in other paragraphs.

[fruitloop]

It is leading edge.....Length is as per the Piccies a distance of 3 cooling holes...and depth is 3.024 MM.Also as can been seen from the piccies the Concave side of the blade now has Convex centre...for the middle 6 centre cooling holes..