Although we’re going to discuss engine failure, it is encouraging to note that with more than 13,000 engines delivered and more than 125 million hours of flight time, the TPE331 is one of the most reliable and proven turboprop engines in the world. Designed in 1959 and certified in 1965, the TPE331 was the first Honeywell turboprop engine. It was developed for multiple applications within military, regional airline, agricultural and general aviation aircraft. Recent data shows that over the last 12-month period examined (2015-2016), there were only 8 inflight shutdowns (IFSD) reported from more than 1.3 million total engine hours operated for that same time period.
There are two types of engine failure, which we define as an incident that will result in no thrust being provided by one of the engines. The first is engine flame out. Flame out occurs if there is an interruption in either the fuel or airflow, or both.
With an engine flame out, you have the benefit of being able to consider an engine restart. Flame outs are caused by inlet icing, fuel mismanagement, or anything that can restrict the flow of fuel or air.
The second type of engine failure is engine fire or severe damage. An engine fire involves component failures, which increases the urgency to act. With an engine fire or any other condition involving component failures, there can be no engine restart considerations.
Examples of causes of severe damage are bearing failures, turbine wheel or blade failure, propeller shaft coupling failure, or the failure of any other internal rotating component.
The second most important action involving an engine failure is recognizing the problem.
The first noticeable sign of an engine failure probably will be a sudden yaw. The failed engine no longer provides thrust and instead causes additional drag, further increasing the potential for yaw if uncorrected. You may hear a surge or some other irregular sound coming from the failed engine, or maybe even detect an odor of fuel or oil.
More importantly, if you’ve got a strong cross scan of your engine instruments, you’ll notice the failure almost immediately. Also, you’ll likely get an auto ignition light. But the absolute most definitive indication of an engine failure is the RPM indicator, since it provides information directly relating to the rotation of the engine components, without which there can be no thrust.
However, the single most important action before identifying the problem should be in the front of every pilot’s mind: aircraft control. Maintaining control and simply flying the airplane is the single biggest priority ANYTIME there is any problem with the airplane’s flight characteristics, especially and more specifically with engine failures.
Managing an engine failure is one thing; avoiding one is another. Calculating and complying with the appropriate reference torque prior to every takeoff can provide numerous benefits ranging from safety (takeoff assurance) to engine health and trending as well as wear reduction.
Before you fly make sure you have available the most accurate information about your aircraft and conditions, execute the takeoff using appropriate reference torque, be vigilant of engine instrument indications, and maintain proper handling technique. Fly safely and strive to always understand the current condition of your engines.
Please remember that these tips are intended to be supplemental to the published operating procedures. For a complete study on aircraft planning and operations for takeoff, please refer to the procedures and recommendations published in the FAA/CAA-approved Airplane Flight Manual (AFM) and POM for the appropriate make and model Twin Commander. As always, pilots can make the difference in engine operating life and maintenance costs.
For additional questions on this subject or any other TPE331 engine-related issues, please don’t hesitate to contact Rob Erlick, Honeywell Engines Program Pilot, at (480) 399-4007 or Flight Technical Services at FTS@Honeywell.com.