Up close and personal with DC-7 tankers: engine maintenance (1 of 2)

 

 

The other day Larry Kraus and I were continuing our e-mail exchanges about DC-7 engines when he shared some interesting details on the process of how Butler changes out a bad engine for a good engine. I had wondered how aircraft engines are replaced, so I was very interested in what Larry had to say:

One point of interest concerning the DC-7 engine installation is that the engine, prop, oil system (oil tank/cooler and all lines) and all of the accessories are mounted in a Q.E.C. (Quick Engine Change) assembly. The British call this Q.E.C. a "Power Egg". If you look at the Q.E.C./Power Egg, you can probably see where the term originated, especially if you think of the Q.E.C. without the engine stand.

The pictures here show an engine that Butler brought to us for Tanker 66 in Fairbanks in 1983. The engine itself weighs about 4,400 lbs. The Q.E.C. when it's ready to install weighs a bit over 6.000 lbs. These picture are in sequence, including photos giving a good view of what a Q.E.C. looks like out of the engine stand.

These really are Quick Change assemblies. The record for Butler for an engine change is truly amazing.I was flying as co-pilot to Laddie Lash in 1979 in the old Tanker 67 on a fire near Klamath Falls. We shut #4 engine down because of smoke from an oil leak and flew to Redmond. The problem would take a while to repair and a Q.E.C. was ready that had been run the day before on a test stand.

There were no complications and it took right at two and a half hours from the time we parked in front of the hangar to starting to taxi out for a test flight. The test flight went okay and we were back flying on the fire within four hours of shutting the engine down. That's a record,but it isn't unusual to have the old engine removed and the new one ready to run within four hours.

As I understand it, the Q.E.C. is used for many tankers, and the Q.E.C. can take some time to build. For example, Larry tells me that "It takes a long time to build up a Q.E.C. when you start with a bare mount and an engine in a can. For the DC-7 Q.E.C. at Butler, it takes around 3-4 months per Q.E.C. in the winter with two or three guys working on it."