Re: JT-8D Hush Kits

From:         David Lednicer <>
Date:         23 Aug 95 23:38:31 
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	There are many different alternatives available to the owners of
JT8D powered aircraft when it comes to quietening their aircraft.  Here
is a list of the alternatives I know of:

All JT8Ss:

1) P&W offers a bypass/core mixer, which I believe is called the "Mod 9"

2) There is also an inlet guide vane mod available, which moves the IGVs
forward to reduce inlet borne noise.


1) ABS (Airborne Express, now ABX/Burbank Aeronautical/Shannon(?))
hushkit, consisting of a exhaust mixer.  From pictures I have seen, I
believe that this is a exhaust/external air mixer, which would imply that
there is also a core/bypass mixer installed internally.  Airborne Express
and Northwest Airlines are adding this mod to their fleets.

2) At one point, there was a company built along the same lines as
CAMMACORP (who did the DC-8 reenginings), with many of th same people,
developing something, but this has gone quiet.


No hushkit is needed to meet Stage 3.

Aerospatiale Caravelle

Most of these aircraft have left active airline service.

Dassault Mercure

The 11 aircraft built have all been retired.

727-100s and -200s

1) Federal Express offers a core/bypass mixer which allows low GW
aircraft to meet Stage 3.  Besides Fedex, the Trump Shuttle (US Air) and
others have this mod.

2) Valsan (now Rohr) offers a reengining mod.  In this case, the outboard
engines are replaced with JT8D-200s from MD-80s and the center engine has
the thrust reverser removed and a core/bypass mixer installed.
Approximately 20 aircraft were modified by the time Valsan closed up
shop.  Most of the modified aircraft are 727-200s, but there were some
727-100s modified.  Rohr is restarting this program.

3) UPS is having Dee Howard reengine their entire fleet of 727s with RR
Tays.  I have seen some these aircraft in service.

4) Burbank Aeronautical claims to offer something for the 727, but I
haven't seen any details.  This might be the ABS DC-9 kit.


1) Nordam (actually Nordam/Boeing/P&W) offers a mod, that I think includes
the P&W IGV respacing and the Mod 9 internal mixer.  Nordam adds to this
an exhaust/external mixer located within a shroud.  This meets Stage 3, but
I understand that there is a GW trade-off and the mod incurs a 5-7% fuel
burn penalty in cruise.  Customers include Air NZ, Lufthansa and US Air.

2) Sound Solutions was developing a similar mod, but the shroud would
have been retractable to get rid of the fuel burn penalty.  This project
died in 1992.  (I worked on this project)

3) AVRO is also offering a hushkit similar to Nordam's.  I understand it
is STC'ed, but I haven't seen one.

4) GE at one point was claiming that they were going to turn 737-200s
into 737-500 look-alikes.  Given the amount of modification this would
take, it is no suprise that this has gone very quiet.

Lastly on 727 winglets - Valsan certified a winglet mod for 727s (I was
involved in the design effort).  Besides the test article, installed on
an ex-United 727-100, four sets were constructed.  Two were placed with
Delta for evaluation, one set was sold to Amway for their corporate 727
and one set was sold to the Canadian charter operator Royal Airlines.
Despite a measured 5.5% fuel burn improvement, Delta decided to not
proceed with the modification program and returned the winglets.  When
Valsan closed down, the winglet program was bought by Winglet Systems,
which is now pursuing the program.

David Lednicer             | "Applied Computational Fluid Dynamics"
Analytical Methods, Inc.   |   email:
2133 152nd Ave NE          |   tel:     (206) 643-9090
Redmond, WA  98052  USA    |   fax:     (206) 746-1299