Engine Inspections

[Seat62K]

I assume that airlines operating aircraft in those parts of Europe impacted recently by volcanic ash have started more frequent inspections of engines for damage.

I'd be grateful (along with many others, I imagine) to have informed answers to the following questions:

What inspections are being carried out?

To what extent is it possible to gauge damage without dismantling the engine?

Most importantly, what are these inspections showing?

Many thanks.

[Cheesehead56]

I can only speak on the part of my company, a UK based airline. I assume that every company is required to carry out the same maintenance procedures since the ash cloud.

The usual daily inspections of aircraft have been amended to include a more rigourous GVI (General Visual Inspection) in areas where ash may gather or cause damage if encountered. For example, engine intakes, cockpit windows, engine fan blades any externally lubricated areas like lower part of an under carriage shock strut. In addition to this the other, less frequent scheduled maintenance tasks also include specific volcanic ash inspections.

There are many things thats can indicate possible ash damage. Pitted or damaged paint work on radomes, engines, windows. Higher than normal EGT could also be an indicator of engine damage.

We are also doing a lot more borescope inspections on the engine internals. This method of inspection shows up internal damage to an engine extremely well as of yet we have found no damage from ash. There are other actions and inspections to be carried out if a pilot reports that he or she may have encountered an ash cloud.

As ive mentioned above, as of yet we havent found any damage or contamination. Hope this helps, if you have any other questions, ask away.

[MathFox]

What I understand is that "the airlines" perform boroscope inspections, where they either bring a camera or some lenses and glass-fiber into the engine that allows the mechanic to see whether and to what extent there is a glass deposit inside the turbine; it also allows to see abrasive wear in the compressor. (It is not unlike a doctor using an endoscope on your intestines.)

One can observe/deduct/estimate the ash damage pretty good from these inspections and from other engine parameters (temperatures, rotation speed, fuel flow) that are routinely logged. I have not seen the results, but I would not be surprised to see that most engines show "normal wear" (there always is some ash in the air) and a few show "more than normal wear", meaning that these engines should be overhauled a few months earlier than originally planned.

It remains a bad plan to fly through dense ash clouds, but accepting some additional wear of the jet engines (and overhauling/replacing them earlier) may be more economical for the airlines compared to not flying at all. The impact on safety of (monitored) flying to diluted ash clouds is marginal.

[Seat62K]

I see that EASA is recommending daily inspections for aircraft flying through airspace known to have low concentrations of ash.

[MathFox]

You might be interested in the discussion on the engineers forum:

http://www.pprune.org/engineers-technicians/412910-ground-procedures-ash-detection.html

[Seat62K]

Thank you!

[dubh12000]

The only worry I would have is the blading internals. You cannot boro them on wing.

[HAWK21M]

If the Boroscope Inspection reveals no problem it can go on.Else its to the Shop visit.