Date: 201603
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Duchess 76
Operator: FBO
Operating under: Part 91
Mission: Training
Flight phase: Cruise
Airspace: Class E ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Engine
Component problem: Malfunctioning
Reporter organization: FBO
Reporter function: Instructor; Pilot Not Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Commercial; Flight Crew Flight Instructor
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Landed As Precaution; Flight Crew Overcame Equipment Problem
Contributing factors: Aircraft; Weather
Primary problem: Aircraft

Narrative: I was conducting an End of Course Eval for a Multi Engine Commercial student. We were at 6700 feet when I pulled the right Mixture. The student followed the published procedure very well as it is listed on the Checklist. We went through the trouble shooting check and the engine secure check as published. She was also doing well maintaining 85 knots and holding as much altitude as possible though we were still descending. The conditions were VFR with several layers of clouds from 3000 to 5000 feet and we had plenty of room to have conducted most of the items on the lesson. When I told her she did a good job with the emergency procedure; I stated that she may continue on to the AIRSTART Procedure as listed in the Checklist. Our altitude at this point was around 6200 feet. She followed the procedure well and pitched forward for 100 knots at which point she was ready to push the right prop lever full forward. I was looking at the prop to verify it was twisting to unfeather. Though it did unfeather; I noticed that it didn't twist as much as they normally do. At 100 knots; the prop was not windmilling. At this point we were at an altitude of 5600 and a few hundred feet above a broken layer of clouds. I stated that we needed to proceed to the WITHOUT UNFEATHERING ACCUMULATOR Procedure. I was worried about holding as much altitude as possible to stay clear of the clouds while doing this so I took the controls. I slowed down to 85 and was maintaining my altitude while having to maneuver clear of clouds. I verified each item on the checklist as she was performing and we attempted 4 restart attempts over a time frame of 15 minutes to no avail. By this time the clouds were closing in and becoming a greater concern. I knew that it was clearer to the west and south west so we departed the area heading southwest. I decided this was a good course because we could always have [another airport] as a contingency. In the distance there was a large break in the clouds sufficient to comfortably maneuver the plane with shallow banks and steady control input. As we descended down; I could see [the destination airport] quite clearly. We listened to the ATIS and proceeded inbound calling Tower at an altitude of 2100 feet. At this point; I did not think it was pertinent to attempt any more restarts and figured the best measure was to [advise ATC] and land. Our groundspeed was around 76 knots with 95 pegged on the Airspeed. Tower had 4 aircraft on final. We were still 6 NM out I was flying the plane fine so I waited until 4 NM out to [request ATC] to clear up the final as much as practical for me inbound. The plane was much more stable at 95 knots so I elected to keep my speed up while maintaining the glide path locked. Wind was approximately 070 11G17 at the time. We confirmed that everything regarding the right engine was secured previously according to the engine secure check. I transitioned to 85 on a quarter mile final and set the flaps to 10 degrees then 20 degrees. The plane slowed to 85. When I knew the field was made I reduced power to come in over the numbers at about 50 feet up. We landed soft and smooth on the 1000 foot markers without event. We shut the plane down on taxiway. I requested a tug back to the ramp. The one thing I didn't do was clear the engine with the mixture lean between each attempt to restart. I thought about it after the third try; but the clouds were not conducive to allow for a long period of time to get the thing going. After landing and during the debrief; I discussed to the student that she did a very good job making this event uneventful. She did a good job turning the plane towards [the airport] while we still in the trouble shooting phase. I made note that though we were heading towards [the airport]; we had left the comfort of a great big clear area that would've come in real handy when we pitched down to attempt the WITH UNFEATHER ACCUMULATOR procedure. We discussed that it would've been nice to havethat hole during all the unforeseen circumstances that would later arise trying to restart the right engine.




Synopsis: BE76 Duchess flight instructor reported that; while providing multiengine flight training; the right engine would not fully unfeather after practicing engine out procedures.