PPRuNe Forums - View Single Post - New CHC S-92
Thread: New CHC S-92
View Single Post
Old 13th Nov 2007, 15:30
  #104 (permalink)  
HeliComparator
 
Join Date: Aug 2004
Location: Aberdeen
Age: 67
Posts: 2,093
Received 43 Likes on 22 Posts
Nick

Yes a good TCDS. You fail to mention the equivalent safety findings nor the special conditions which some might consider to be fudges. Personally I would let you off with them though 'cos I'm a nice chap.

However it has to be pointed out that the crisp piece of paper does not do much for safety. JAR29.927 (c) says (and I guess FAR29.927 is the same)

(c) Lubrication system failure. For lubrication systems required for proper operation of rotor drive systems, the following apply:
(1) Category A. Unless such failures are extremely remote, it must be shown by test that any failure which results in loss of lubricant in any normal use lubrication system will not prevent continued safe operation, although not necessarily without damage, at a torque and rotational speed prescribed by the applicant for continued flight, for at least 30 minutes after perception by the flight crew of the lubrication system failure or loss of lubricant.
And yet despite apparent compliance with this para, we know that the S92 cannot run for 30 mins following loss of gearbox oil. Quite how you got away with this cheat eludes me, but I can only assume that you fooled them into thinking it was "extremely remote". I guess that was because your fatigue evaluation didn't turn up the weak gearbox casing? Neither did your FMEA consider the consequences of the oil pump drive failure.

Since there have now been 2 in-flight incidents (that I know of, perhaps there are more?) where an S92 had a major loss of lubrication (in 1 case both pumps, in the other the oil), it can no longer be considered "extremely remote" so are you going to change the TCDS to show non-compliance? No, I didn't think so and that is why your tcds is not really worth the paper its written on. Its about as accurate and reliable as a Sikorsky performance graph. What other fudges are lurking in there that we have yet to find?


HC
HeliComparator is online now