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 737, 1x Reverser Inop And Perf Calculations
 smartt1982 From United Kingdom, joined Nov 2007, 225 posts, RR: 0Posted Tue Sep 11 2012 12:41:58 UTC (3 years 8 months 2 weeks 3 days 18 hours ago) and read 5000 times:

 Hi Hoping someone can share some information regarding performance calculations on the 737 with 1 reverser inop. In our European operator we have a particular set of rules in how we calculate performance with 1 reverser inop and I was just wondering if it is just our company or is dictated by legislation. We calculate take-off performance with 1 reverser inop from a WET runway but we reduce max weight by 1050kg and reduce V1 by 2 knots. For take-off calculations from a slippery/contaminated runway with 1 reverser inop we calculate distance using the “no reverse thrust” (we don’t take credit for the remaining one) For inflight landing calculations onto a runway with 1 reverser inop we use the “No reverse thrust option”. I realise that it makes sense to do so but I cannot seem to find reference to it from the relevant legislation such as EU OPS but in CS25 I found this under CS25.125 . “(g) If any device is used that depends on the operation of any engine, and if the landing distance would be noticeably increased when a landing is made with that engine inoperative, the landing distance must be determined with that engine inoperative unless the use of compensating means will result in a landing distance not more than that with each engine operating. [Amdt. No.:25/3]” Is it referring to do or is that something that the manufacture has to take account of with all reversers working?
 Fabo From Slovakia, joined Aug 2005, 1245 posts, RR: 0 Reply 1, posted Tue Sep 11 2012 16:53:14 UTC (3 years 8 months 2 weeks 3 days 14 hours ago) and read 4973 times:

 Boy, is that some lawyerspeak. Anyway arent operators supposed to calculate every landing/takeoff, at least on dry surface, without reversers?
 The light at the end of tunnel turn out to be a lighted sing saying NO EXIT
 tdscanuck From Canada, joined Jan 2006, 12710 posts, RR: 78 Reply 2, posted Tue Sep 11 2012 18:14:46 UTC (3 years 8 months 2 weeks 3 days 13 hours ago) and read 4957 times:

 Quoting Fabo (Reply 1):Anyway arent operators supposed to calculate every landing/takeoff, at least on dry surface, without reversers?

The operators are supposed to use the certified data. It's the OEM's that have to do the certified data without reversers for a dry runway.

However, the 737 is an oddball in being one of the few aircraft to certify the *wet* performance including reverse thrust. That's not normal. Since they did that, you need to correct the wet performance numbers if you have an inop reverser.

This is sort of tacitly regulatory...you need to use certified performance data and, for the 737 on a wet runway, that data included reverse thrust so you need to account for it. For most other aircraft, the certified data never included the use of reverse thrust so you don't need to correct for it being missing.

Tom.

 YYZatcboy From Canada, joined Apr 2005, 1202 posts, RR: 0 Reply 3, posted Tue Sep 11 2012 20:25:11 UTC (3 years 8 months 2 weeks 3 days 10 hours ago) and read 4933 times:

 Here our Aerodata computer makes weight calculations but we also add an additional 20% factor to all landing distances.
 DHC1/3/4 MD11/88 L1011 A319/20/21/30 B727 735/6/7/8/9 762/3 E175/90 CRJ/700/705 CC150. J/S DH8D 736/7/8
 smartt1982 From United Kingdom, joined Nov 2007, 225 posts, RR: 0 Reply 4, posted Wed Sep 12 2012 08:40:22 UTC (3 years 8 months 2 weeks 2 days 22 hours ago) and read 4861 times:

 Quoting tdscanuck (Reply 2):However, the 737 is an oddball in being one of the few aircraft to certify the *wet* performance including reverse thrust. That's not normal. Since they did that, you need to correct the wet performance numbers if you have an inop reverser.

So other aircraft eg 757/767/777 etc all were certified on wet runways without having to use thrust reversers? How come it was differnet for the 737?

 tdscanuck From Canada, joined Jan 2006, 12710 posts, RR: 78 Reply 5, posted Wed Sep 12 2012 17:48:14 UTC (3 years 8 months 2 weeks 2 days 13 hours ago) and read 4819 times:

 Quoting smartt1982 (Reply 4):So other aircraft eg 757/767/777 etc all were certified on wet runways without having to use thrust reversers? How come it was differnet for the 737?

The others don't have certified wet runway performance data (they have advisory data). If you pull out a 757 FCOM it will just have a Takeoff Speeds table. A 737 FCOM has two...Takeoff Speeds - Dry Runway and Takeoff Speeds - Wet Runway.

I suspect that the 737 did it because short field performance is a lot more important for them than for any other Boeing aircraft, but I'm not sure about that.

Tom.

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