Bonanza 35
Flight Crew Multiengine; Flight Crew Private; Flight Crew Instrument
Flight Crew Last 90 Days 4.5; Flight Crew Total 744.7; Flight Crew Type 384
Distraction; Situational Awareness
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter CFTT / CFIT
Flight Crew Landed As Precaution; Flight Crew Became Reoriented
Human Factors; Aircraft
I departed for my second break-in flight on a freshly overhauled engine. The break-in procedure instructed me to fly below 6;000 MSL in order to keep manifold pressure as high as possible so the piston rings will seat properly; and make power changes every 30 minutes (for 1 to 5 minutes) before returning to max cruise settings. My first break-in flight showed me that 5;500 MSL would not quite produce 24 inches of manifold pressure (26.5 is max cruise setting) so I intended to stay lower on the next flight. I planned to fly West; over the railroad tracks with a touch and go at ZZZ and ZZZ1 then return. Because that route is over sparsely populated areas I decided that I would fly at 500 AGL to keep the manifold pressure up. This was my first mistake: my airplane does not give altitude readings in AGL; I was basing my altitude decision on airport altitudes enroute with no thought about the actual terrain around these airports. For some reason that didn't occur to me before this flight. So after take-off I climbed to 4;700 MSL and set the autopilot to hold that altitude and followed the railroad tracks. As I approached ZZZ I reduced power for the touch and go and switched the radio to get the weather there; as I set the pressure altitude I noticed the cylinder head temperature starting to climb. This became my focus for the duration of the flight- I became so distracted by this temperature reading I basically forgot to fly the airplane. My initial response was to increase the fuel mixture and begin a descent to increase the airflow; when that didn't lower the CHT I broke off the approach and put it in a shallow climb and returned to the railroad tracks headed West. This is where I became more of a passenger than a pilot. I could not take my focus off the CHT; I utilized the autopilot to maintain heading and I tried to keep it in a shallow climb while I watched the temp gauge. The autopilot hunted left then right doing its best to hold heading so I disconnected the autopilot and hand flew; eventually reaching 4;700 MSL and watching the CHT gradually decreasing. Then I realized I needed to go higher because the altitude at ZZZ is 4;400 MSL; I should be at a minimum of 4;900. At this point I recognized that I was too far behind the plane and made the only good decision that day- I turned back. Unfortunately my focus was still on that CHT gauge; and I still had to figure out how to land the plane without the CHT going to redline. So I tried some different power settings on the way back; as I approached ZZZ3 I started a simulated approach to monitor the effect on CHT. Reducing the RPM first seemed to help keep the CHT from rising as quickly and beginning the descent at the same time helped even more. But now I realized I was too low again; ZZZ3 is 4;500- I should have been at 5;000 MSL to be at least 500 AGL. I was not prepared for this flight; I should have spent more time flight planning; I took for granted that it was just a local flight for engine break-in; this should have been treated like any other cross country flight. Because I was focused on the engine break-in rather than the actual flight I almost became the next CFIT statistic. Every flight should be treated with the same level of planning regardless of the reason for the flight.
BE35 pilot reports flying a new engine break in flight at 5;500 feet and returning. The next flight is planned at 500 AGL to increase manifold pressure. When CHT begins to rise few options remain.