Mary YES
Flying as a co pilot at night in a Citation from Biggin Hill to Majorca! climbing out through 20,000 feet I looked at the German Captain and thought my eyes had gone funny.
his face was shimmering! Then I smelt it ! Thick acrid smoke which was streaming out of the vents and filling the cabin.
this got worse until you could hardly see the passengers in the back.
The stuff was dense and choking so on with the oxygen masks a mayday and a quick descent back to Biggin Hill.
we vented the Cabin because it was now almost impossible to see and were given a straight line over Gatwick and an uninterrupted descent.
It was pitch black when we landed at Biggin to be met by a group of fire engines.
The PAX were terrified and all my clothes stank of burning plastic.
The fault was found to be a fan motor which caught fire in the air circulation system. All good for the soul
I will also add an engine failure in a fairly new Seneca 4 at 300 feet and gross weight! Three rocker shafts sheared and realising if I pulled the prop lever back and stopped the engine I was not going to go anywhere fast but down.
So I kept one hand on the prop lever in case the unit went bang and used the little power from that engine to coax a climb.
Levelling at 800 feet the engine was shaking so badly I had to shut it down made a Mayday call and landed single engine.
Continental insisted the unit had been over boosted on takeoff to shear the rockers shafts like that until a PAX in the back showed a film he had taken of the takeoff with the engine gauges showing they were perfectly set on takeoff.
Continental then discovered the engine rocker shafts had been incorrectly torqued at manufacture and replaced the 100 hr unit with a new one within two weeks.
again all good for the soul
Many other instances where maybe I should have but didn't
Pace