TBO and airworthiness

"Capt. Geoffrey Thorpe" The Sea Hawk at wow way d0t com wrote in message
...
"karl gruber" wrote in message
...
What is B-10, B50 etc?


Karl
Always top post


B-10, B-50... are the expected hours at which 10%, 50%, etc. are expected
to fail. The "B" is from "bearing" - the orignal theorys were developed
to predict the life of ball bearings, but the termanology is now used for
everything. The Weibull distribution is usually used to "fit" durability
data and determine these values.

If TBO is B-10, then, in most cases, it would seem silly to overhaul at
TBO, if it is B-90, then it would be optimistic to expect to make TBO...

Or, TBO could be a number that some engineer pulled out of the air (to put
it politely).


I don't think TBO is a projected or average expected "point of failure". I
believe they'd call that "Expect Life Expectancy".

"Robert M. Gary" wrote in message
ups.com...
On Apr 10, 9:12 pm, Jim Stewart wrote:
Does an engine past TBO make an aircraft
non-airworthy? I can't seem to find a
straight answer on the web.

Assuming you can find an IA willing to sign an annual then no.


Pardon?

"Robert M. Gary" wrote in message
oups.com...
On Apr 11, 10:16 am, Newps wrote:
Robert M. Gary wrote:
On Apr 10, 9:12 pm, Jim Stewart wrote:

Does an engine past TBO make an aircraft
non-airworthy? I can't seem to find a
straight answer on the web.

Assuming you can find an IA willing to sign an annual then no.

Have you found that to be a problem? I haven't. My mechanic flies his
180 on pipeline patrol and is 1000 over TBO on his 470. Another friend
also flies pipeline in his PA12 and went 3600 hours before he topped it
and 7000 hours before he finally majored it, that's a lot of 100 hour
inspections.

Yes, many IA's I've worked with refuse to sign after 200 over TBO. Its
probably a liability issue.


Sounds like a competency issue - on what basis did they 'fail" the aircraft?

Yes, many IA's I've worked with refuse to sign after 200 over TBO.
Its probably a liability issue.


Sounds like a competency issue - on what basis did they 'fail" the
aircraft?

They don't have to fail anything. If it's not returned to service, the
owner is at liberty to find another IA who is willing to return it to
service. An IA is not obligated to explain why he chooses not to return
an aircraft to service.

"Dave Butler" wrote in message
...

Yes, many IA's I've worked with refuse to sign after 200 over TBO.
Its probably a liability issue.


Sounds like a competency issue - on what basis did they 'fail" the
aircraft?

They don't have to fail anything. If it's not returned to service, the
owner is at liberty to find another IA who is willing to return it to
service.

Note the "" around _fail_.

An IA is not obligated to explain why he chooses not to return an aircraft
to service.

I seriously doubt they would stay mute on the subject.

Matt Barrow wrote:
"Dave Butler" wrote in message

An IA is not obligated to explain why he chooses not to return an aircraft
to service.

I seriously doubt they would stay mute on the subject.

Correct, but if the explanation is not satisfactory to the AC owner, the
IA can just say thanks for your business, next time go elsewhere.

"Dave Butler" wrote in message
...
Matt Barrow wrote:
"Dave Butler" wrote in message

An IA is not obligated to explain why he chooses not to return an
aircraft to service.

I seriously doubt they would stay mute on the subject.

Correct, but if the explanation is not satisfactory to the AC owner, the
IA can just say thanks for your business, next time go elsewhere.

If they would not sign off my aircraft merely because it was 200 hours over
TBO, regardless of the condition of the engine, bet yer ass I'd go somewhere
else. The IA wouldn't have to ask me to go elsewhere.

On Apr 12, 8:42 am, "Matt Barrow"
wrote:
"Dave Butler" wrote in message

...



Yes, many IA's I've worked with refuse to sign after 200 over TBO.
Its probably a liability issue.

Sounds like a competency issue - on what basis did they 'fail" the
aircraft?

They don't have to fail anything. If it's not returned to service, the
owner is at liberty to find another IA who is willing to return it to
service.

Note the "" around _fail_.

An IA is not obligated to explain why he chooses not to return an aircraft
to service.

I seriously doubt they would stay mute on the subject.

In fact, once the inspection has started, the IA is required by
FAR to sign the aircraft off as un-airworthy
and give the owner a list of things to fix to make it airworthy. Part
43.

But ahead of time, you could quiz him informally about what
he would do. If he has an idea about TBO that you don't
like, you could learn that before you start.

Bill Hale A&PIA

Dave Butler wrote:


Yes, many IA's I've worked with refuse to sign after 200 over TBO.
Its probably a liability issue.


Sounds like a competency issue - on what basis did they 'fail" the
aircraft?


They don't have to fail anything. If it's not returned to service, the
owner is at liberty to find another IA who is willing to return it to
service. An IA is not obligated to explain why he chooses not to return
an aircraft to service.

He's supposed to make a log entry regarding the
results of his inspection isn't he? Even if the
FAR didn't specifically require such an entry,
common business ethics and practices would demand
it should the owner request it.

An IA is not obligated to explain why he chooses not to return an aircraft
to service.


In fact, once the inspection has started, the IA is required by
FAR to sign the aircraft off as un-airworthy
and give the owner a list of things to fix to make it airworthy. Part
43.

Oh. I'm sure you're right. Thanks for the correction. Dave