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Faro
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737-100/200 Certificated In Just 8 Months?

Tue Jul 17, 2012 10:30 am

http://www.b737.org.uk/history.htm

From the above link:

Quote:
9 Apr 1967: First flight of 737-100.

8 August 1967: First flight of 737-200, the 5th 737 to fly.

15 Dec 1967: FAA Type certification of 737-100 and -200.

I suppose there is the commonality of the fuselage/nose with the 707/727 but it stills seems miraculous that certification just took 8 months for:

- 2 different airliner versions;
- with a novel engine installation; and
- IIRC, the latest, state of the art flight control system (later implemented on on the 747).

How was this acheived? Was it just a case of everything going right all the time?


Faro

[Edited 2012-07-17 03:50:50]
The chalice not my son
 
citationjet
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RE: 737-100/200 Certificated In Just 8 Months?

Tue Jul 17, 2012 11:37 am

Your dates looks correct, except the FAA TCDS shows 737-200's TC was granted December 21, 1967.
An amazing feat in today's certification environment. I assume that much of this is due to a lower level of FAA oversight and scrutiny, which still resulted in a very safe aircraft. Makes on wonder if today's certification requirements add much more than complexity, time and money.
Boeing Flown: 701,702,703;717;720;721,722;731,732,733,734,735,737,738,739;741,742,743,744,747SP;752,753;762,763;772,773.
 
rfields5421
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RE: 737-100/200 Certificated In Just 8 Months?

Tue Jul 17, 2012 1:15 pm

DC-9

First flight Feb 25, 1965
Certification Dec 8, 1965

One factor cited which is very different than today is that Douglas put five completed aircraft into the flight certification program. Today one, sometimes two aircraft are used. It is simply too costly for the manufacturer to 'waste' airframes on the certification process.
 
BoeingGuy
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RE: 737-100/200 Certificated In Just 8 Months?

Tue Jul 17, 2012 4:25 pm

Quoting rfields5421 (Reply 2):
Today one, sometimes two aircraft are used. It is simply too costly for the manufacturer to 'waste' airframes on the certification process.

Didn't the 787 use six airframes for certification?
 
tdscanuck
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RE: 737-100/200 Certificated In Just 8 Months?

Tue Jul 17, 2012 5:07 pm

Quoting faro (Thread starter):
How was this acheived? Was it just a case of everything going right all the time?

Two big contributors:
1) Boeing already had the 367-80 (aka "Dash 80") in flight. They knew almost all the answers, which really cuts down the number of surprises during certification.
2) The number of FAR's to comply with was *far* lower back then.

Quoting BoeingGuy (Reply 3):
Didn't the 787 use six airframes for certification?

Eight.

4 dedicated flight test aircraft for RR, 2 dedicated flight test aircraft for GE, plus ZA102 for RR ETOPS/F&R and ZA236 for GE ETOPS/F&R.

Tom.
 
boeingfixer
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RE: 737-100/200 Certificated In Just 8 Months?

Tue Jul 17, 2012 5:10 pm

Quoting faro (Thread starter):
- IIRC, the latest, state of the art flight control system (later implemented on on the 747).

Actually the B737-100/200 flight control system wasn't that complicated and was more like the one on the B727. The B747 flight control system is immensely more complicated and state-of-the-art than the B737.

Cheers,

John
Cheers, John YYC
 
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Faro
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RE: 737-100/200 Certificated In Just 8 Months?

Tue Jul 17, 2012 5:41 pm

Quoting tdscanuck (Reply 4):
1) Boeing already had the 367-80 (aka "Dash 80") in flight. They knew almost all the answers, which really cuts down the number of surprises during certification.

Does that mean that the initial design 737 was intentionally made to resemble the 367-80 as close as possible? The 737 seems on the face of it to be quite a different beast, substantially lighter, with a new smaller, high-lift wing and new empennage.


Faro
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tdscanuck
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RE: 737-100/200 Certificated In Just 8 Months?

Tue Jul 17, 2012 6:09 pm

Quoting faro (Reply 6):
Does that mean that the initial design 737 was intentionally made to resemble the 367-80 as close as possible?

I don't think that was an explicit design goal, but it's basically the same nose/flight deck/fuselage and the systems are pretty close to the 727. They reused a lot of material from the Dash-80/707/727.

Quoting faro (Reply 6):
The 737 seems on the face of it to be quite a different beast, substantially lighter, with a new smaller, high-lift wing and new empennage.

That's true, but those are rarely the things that get you in flight test. It's structure (no real philosophy or material or process change from the 727), technology (no real change from the Dash-80/707/727), systems (no real change from the 727) that usually get you.

Tom.
 
aeroweanie
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RE: 737-100/200 Certificated In Just 8 Months?

Wed Jul 18, 2012 6:55 pm

Actually, its pretty remarkable that the 737-100 was certified so fast. I know that they had a flight test incident involving severe damage to the slats at dive conditions. They also had the thrust reverser problem, where the use of the thrust reversers actually increased stopping distances. Fortunately for Boeing, landing lengths don't take credit for thrust reversing.
 
BoeingGuy
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RE: 737-100/200 Certificated In Just 8 Months?

Wed Jul 18, 2012 7:31 pm

Quoting aeroweanie (Reply 8):
They also had the thrust reverser problem, where the use of the thrust reversers actually increased stopping distances. Fortunately for Boeing, landing lengths don't take credit for thrust reversing.

Before someone asks the obvious question "why", I think I know. The original short engine on the -100/-200 was very close to the wing. Reverse thrust blew air back over the wing which gave some lift, thus decreasing the effectiveness of the brakes. The solution was to lengthen the tail cone of the engine a bit, which pulled the reverse thrust away from the wing.
 
OldAeroGuy
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RE: 737-100/200 Certificated In Just 8 Months?

Wed Jul 18, 2012 7:57 pm

Quoting BoeingGuy (Reply 9):
The original short engine on the -100/-200 was very close to the wing. Reverse thrust blew air back over the wing which gave some lift, thus decreasing the effectiveness of the brakes. The solution was to lengthen the tail cone of the engine a bit, which pulled the reverse thrust away from the wing.

Sort of correct. The lift came more from the high pressure area the reverse thrust created under the wing.

As you say, the solution was lengthening the cowling to put the reverser aft of the wing.

A case where using an exisiting design (727 thrust reverser) didn't work out in practice.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
N243NW
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RE: 737-100/200 Certificated In Just 8 Months?

Wed Jul 18, 2012 10:56 pm

Quoting OldAeroGuy (Reply 10):
As you say, the solution was lengthening the cowling to put the reverser aft of the wing.

Didn't they also reorient the buckets from straight up and down to being more angled? I can't remember for sure.
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OldAeroGuy
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RE: 737-100/200 Certificated In Just 8 Months?

Wed Jul 18, 2012 11:13 pm

Quoting N243NW (Reply 11):
Didn't they also reorient the buckets from straight up and down to being more angled? I can't remember for sure.

Yes, the extended tail pipe angled the reverser buckets. This resulted in fuselage sonic fatigue issues many years later.

I believe the initial reverser orientation was left and right rather than up and down.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
OldAeroGuy
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RE: 737-100/200 Certificated In Just 8 Months?

Wed Jul 18, 2012 11:24 pm

Here are pictures showing the original thrust reverser design:

http://www.airliners.net/photo/Lufth...d=cabd947cb5cb6c1eaa54c2e042798cef

And the modified design:

http://www.airliners.net/photo/Lufth...d=cabd947cb5cb6c1eaa54c2e042798cef

Looking at the original design, it confirms my recollection that the reverser initial reverser operation deployed the buckets left and right.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis

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