aircraft lifespan

[purplehelmet]

hi guys, i was just wondering what or who govens the lifespan of an airliner. for example is there a limit on how many total hours an airliner can fly,or does it go by the number of rotations it does, or do the caa decide its to old to continue? or is it up to the airline its self.

[Intruder]

As long as it can pass all its inspections, it can fly forever. Look at all the DC3s and DC6s still flying!

We retired our oldest 747 this year; it was built in 1973.

[purplehelmet]

thanks for that intruder, wow thats some miles on the clock, can you please tell me was it still flying passengers all that time or was it a cargo aircraft? and any idea if it was the original engines? thanks.

[Seat62K]

I would imagine that once maintenence costs rise significantly, and reliability suffers, airlines think about getting rid of old aircraft. There must be a point when it's simply not worth spending money to keep an aircraft in the air, good money after bad and all that. (A bit like an old car, really.)

There must be much more to airlines' calculations, though. For example, fuel burn compared with newer aircraft, fuel prices, the cost of new/newer aircraft, the availability of credit to purchase these etc., etc.

(Having said that, though, I did wonder whether airlines' phasing out of older 747s had something to do with the TWA crash.)

[purplehelmet]

thanks seat62k. what set this off was a mate recently flew with jet2.com and made a comment on how old there fleet is (average 21 yrs) compared to other uk carriers, we know some older aircraft are restricted in the uk because of noise etc,but i guess in answer to my question there no limits as long as they are airworthy. thanks guys.

[Planemike]

A factor not mentioned so far is "passenger appeal". Something new and shiney is going to appeal more than some dated bit of functional kit.

Planemike

[purplehelmet]

thats true mike but but i think in large when joe public books his holiday hes more concerned about the price rather than the age and apperance of the aircraft, also i must say that i think the jet2 colour scheme looks great and makes their aircraft look shiney and new, especially the 757s with the wing tips.

[Planemike]

ph...... Point taken, with many modern aircraft it is possible to disguise their real age fairly well, the Jet2 fleet being a case in point. Joe public would be hard pressed to tell the difference between a 25 year old 737 and a four year old one. It was not the case back in the 60s and 70s when props were being phased out and jets being brought in. Think most punters could tell the difference between a DC6 and a Comet, par example !!!!

Planemike

[glhcarl]

A factor not mentioned so far is "passenger appeal". Something new and shiney is going to appeal more than some dated bit of functional kit.

That is why airlines install new interiors on older airframes. Passengers get very little opportunities to see the exterior of the aircraft but see the interior the whole time they are in flight. Up-grading an interior is much less expensive than a new airframe.

[N707ZS]

Presume fatigue life must eventually come into play on some airframes.

[Tinwacker]

Purplehelmet:
The manufacturer will normal set the airframe life and after consulting FAA or CAA etc for their input.
For most aircraft it's pressurisation cycles that normally effect the end life of an airframe. Hours will just give you a jaded aircraft and as previously mentioned cost of maintenance and upkeep and high fuel burn normally sends it to the desert... The long range companies tend to average high time but lower cycles hence many old B747s and the like are still trucking, but take the short range types doing hops the hours flown are lower but cycles are very much higher and life tends to end quicker.
A famously reported Aloha B737 was lowish hours compared to the cycles and felt fatigue badly.

TW

[Mr @ Spotty M]

It does indeed N707ZS.
To correct what has been posted before.
All Airbus aircraft have a DSG (Design Service Goal) in Flight hours & cycles.
Some older Airbus a/c have a ESG (Extended Service Goal) or LOV which is the same thing, which is an extension of the flight hour & cycle life.
Once the ESG or LOV limit is reached it no longer meets FAA or EASA requirements and ends up being used for Cola cans.
Boeing however do not have such a system yet, but has already published figures of what the life limit is going to be on current Boeing types.
This will come in very shortly due to FAA ageing fleet requirements.
I hope this helps answer your question purplehelmet.

[Intruder]

thanks for that intruder, wow thats some miles on the clock, can you please tell me was it still flying passengers all that time or was it a cargo aircraft? and any idea if it was the original engines? thanks.

AFAIK, it was a freighter all its life. That means it operated at higher average gross weights its entire life.

It is unlikely the original engines were on the airplane, because engines are routinely swapped among airplanes as they need repair or refurbishment. I suppose it is possible 1 or more randomly came back to the airplane, but it is also more likely those "original" engines are still on another airplane, with many new parts.

[Planemike]

That is why airlines install new interiors on older airframes. Passengers get very little opportunities to see the exterior of the aircraft but see the interior the whole time they are in flight. Up-grading an interior is much less expensive than a new airframe.

Exactly my point ........ see post 8 above.

Planemike

[purplehelmet]

thanks all for your helpful answers
tw. i remember watching a t.v. programme about the aloha 737, nearly all pax and crew had a very lucky escape, didnt it have some thing to do with it operating in a salty climate that caused metal fatigue?

[glhcarl]

remember watching a t.v. programme about the aloha 737, nearly all pax and crew had a very lucky escape, didnt it have some thing to do with it operating in a salty climate that caused metal fatigue?

The Aloha incident led the FAA and other regulatory agencies to require all OEM's to establish a fatigue life for each of their models. However, once the fatigue life is reached it does not mean that the aircraft must removed from service. What it means is that a series of modifications/inspections must be incorporated. Once these modifications/inspections have been accomplished the aircraft can then continue to be operated, until another established threshold is reached, where addtional modifications/inspections will be rquired. This could go on and on as long as the operator is willing pay for this addtional maintenance.

[aseanaero]

Most turboprops and airliners are scrapped at 30 to 35 yrs of age due to economics, increasing operating and maintenance costs and decreasing dispatch availability (usually avionics, hydraulic and electrical faults) unless they find a second life as a cargo aircraft.

[LN-KGL]

There are number of old aircraft still flying with passengers, and the Northwest (Delta) DC-9-31 N8920E is really good example of that. Her first flight was in January 1967, now almost 43 years ago. In the UK Loganair is flying Twin Otter to Barra, and one of them will turn 30 next year. If we are talking about petrol props, there are a number of Islanders and Trilanders that have turned 30 and still are in passenger service in the UK. Greenlandair uses de Havilland Canada Dash-7 to fly to a number of STOLport on the island, and the oldest turned 30 last February. In other words, there are a number of really old aircraft flying around with paying passengers. The two oldest aircraft I've flown with both flew for the first time in 1943 - a Dragon Rapide and a DC-3 - and I survied.

[fdcg27]

The eternal nine

I thought that someone would mention Northwest and their (now Delta's) DC-9s.
We have flown in various iterations of the eternal nine (DC-9, MD-8X, 717), and have always prefered them to either the single aisle Airbii or the 737.
These things seem to be remarkably well made, with simple systems that can be easily maintained.
The DC-10, despite its early cargo door problems, and the DC-8 seem to be durable aircraft as well.
I'll make a snide coment to the effect that most MD-11s seem destined to be lost in mishaps before they can reach graceful old age.

[LN-KGL]

fdcg27, didn't I mention the Northwest DC-9?