1-11 reverse

[Independance]

Hello

Just found this on: http://www.bac1-11jet.co.uk/

The five failures mentioned here were among the dozen or more engines which were prematurely changed that year, and for some time there was no explanation for this. Eventually, however, the cause was found to be connected with the application of reverse thrust to slow down after landing. As Cedric Flood explained so well in his book A Pilot's Perspective: “The early 200 and 300 series 1-11s had spoilers, but our 400 series (like the 500 series) also had lift dumpers, which were positioned on the top surface of the wing more or less in front of the engines. These were activated by the spoiler lever, but, while the spoilers operated at all times, the dumpers only operated on the ground on landing. American Airlines had the same 400 series 1-11, and they had discovered that when using normal reverse on the short fuselage aircraft fitted with lift dumpers, the airflow to the engine was disturbed, causing temporary overheating, and eventual damage”. It appears that while American Airlines had reported this to BAC, details had not been passed on to other 400 series operators. The problem was not experienced with the longer fuselage 500 series, due to the greater distance between the wing lift dumpers and the engine intakes, and the solution for the shorter fuselage 400 was to use reverse idle instead of normal reverse on landing. Normal reverse was still available, but was to be used only in an emergency or on the rare occasions that a short runway was in use. Subsequently, with this procedure in place, the aircraft were mainly trouble free.

It looked like reverse on 400s were rarely used

Happy 2013!!!

Tomasz

[DaveB]

Thanks for that Tomasz.. an interesting article

I've moved this to E&S as it's not Fsim, strictly speaking. We can use our reversers whenever we wish

Happy 2013 to you too
ATB
DaveB

[Garry Russell]

Interesting and puzzling.

All One-Elevens I've seen seemed to use full reverse.

I've flown on a 475 and it used full reverse even landing at Glasgow.

The lift dumper was introduced on the 300 as optional and the 400 as standard and all 300's had them fitted???

At least, everything I've ever read that's mentioned the dumpers have said that.

One thing never mentioned much and never addressed in plastc modelling is that all One-Elevens after the 200 had 4 inch longer nacelles, all at the front which would close the gap even further.

The 475 was sold as a rough field short field version and I find it difficult to see that being the case if the dumpers were causing and issue as full reverse thrust, aerodynamic and wheel braking is what would be selling it.

Maybe there was something kept quiet...we have some One-Eleven guys here.

[clavel9]

That's one I hadn't heard before. Thanks for posting it. I've also ordered the Cedric Flood book as it looks like an interesting read.

[NigelC]

I don't recall any issues at BIA with the 400s or at Medex with the 475.

The Spey 506 on the 200 was limited to 90% hp rpm for reverse thrust as opposed to the 100.1% for the Spey 511. The 30 second limit on reverse thrust is applicable to both. The only other thing I can recall was normal reverse down to 80kts reducing to idle reverse and reverse thrust cancelled by 60%, however in an emergency the reverse thrust could be used to standstill, there was increased risk of airflow disturbance due re-ingestion of exhaust gases.