ASW-15 Life Limits

[gtomlinson]

I'm curious about the ASW-15's life limit.  From what I understand there is a requirement by the manufacturer for a 3,000 hour general inspection and a total life limit of 6,000 hours.

Is this correct?  How does this effect US registered aircraft?  Anyone been through a 3,000 hour inspection?

Thanks,

Glen


Followup:  I've been doing some searching on line and found this on the Alexander Schleicher factory website:

"The results of fatigue tests with wingspar sections have demonstrated that the service time of the
ASW 15 variants may be extended to 12,000 hours, if for each individual ASW 15 the airworthiness
is demonstrated according to a special multi-step inspection program, which is amended to the Operations
Manual of the ASW 15."

From what I can gather, the ASW15 can have a special inspection done at 3,000 hour intervals to a current life limit of 12,000 hours.  By my calculations that should make the average ASW15 good for around 200 more years based on the reported times and usage rates.  I have not been able to find any information about what exactly a "special multi-step inspection program" consist of, who can preform it and what it would cost.

[Rob Ford]

Glen-
You can e-mail Schleicher for a direct answer about what that involves.
I had a minor question about my -17 and they responded promptly.

info@alexander-schleicher.de

-Rob

[gtomlinson]

Rob,

Good idea, I sent them just such a request.  I'll share their responce with the forum.  I think it's important to fully understand what is involved and required of an ASW-15 to pass a "special multi-step inspection program" every 3,000 flight hours.   

I'm also curious if the inspections are only flight hour oriented.  It would seem to me that these composite material aircraft would "age" while just sitting around.  I've never owned a composite airplane before and I'm trying to get a better grasp on the realities of ownership.

Glen

[Rob Ford]

Glen-

The fiberglass holds up pretty well- there can be some fine surface cracks from weathering, especially UV exposure. Those tend to run in a chordwise direction and aren't very deep. There is a definition somewhere in the service documentation of what constitute significant blemishes. Mostly, those are a minor aerodynamic and a cosmetic issue.

The standard way of building fiberglass sailplane wings results in a several-mm-thick "gel coat" layer which isn't structurally significant. That's the layer that gets the fine cracks, plus, it ages to a dingy yellowish colour.
Some owners eventually refinish the gelcoat and/or apply paint.

ASW-15s before serial number 356 used balsa wood in the wing spar web. There were some issues with decay in the balsa from fungus, so after 356, they used rigid PVC plastic foam instead of balsa.

An AD calls for the ASW-15s with balsa in the spar to be treated with fungicide and have an opening provided to permit inspection of the spar interior. After that, it is just another item on the annual inspection.   

-Rob

[gtomlinson]

I received a prompt reply from Alexander Schleicher GmbH regarding the ASW-15 1,000 hour inspection requirements.  They forwarded documents outlining the inspection process.  I've attached them below.

If I understand the documentation correctly, the first 1,000 hour inspection is required when the airframe reaches 3,000 hours, then again every 1,000 hours until the airframe reaches 6,000 total hours.  It is my understanding that this has been extended again to 12,000 total hours.

It appears to be a straight forward process that an authorized inspector could perform without too great expense to the owner.  That of course would be the next step, to get an idea of the time and cost involved.  Schleicher suggested I contact Eastern Sailplanes here in the USA for that information.