✈️ Aviation Brief — Issue #76
Weekly insights for student pilots and the instructors who train them.
THIS WEEK'S TOPIC
CA.II.B — Powerplant Operation (Commercial Pilot ACS)
1. ACS STANDARDS SUMMARY
The FAA ACS requires the applicant to demonstrate knowledge and practical application of powerplant operation for the installed engine. This includes use of the appropriate checklists for normal, abnormal, and emergency procedures; engine start (including hot and flooded starts), runup, operation, and shutdown; recognition of normal and abnormal engine instrument indications; and corrective actions for common issues such as low oil pressure, rough running, or excessive temperatures. The examiner expects the applicant to perform these actions in the airplane while explaining instrument readings and decisions in real time.
2. THREE COMMON STUDENT MISTAKES
- Rushing the engine start sequence and failing to prime or crack the throttle the correct amount, resulting in flooded or hot-start problems.
- Neglecting to monitor engine instruments during runup, particularly missing a partial magneto drop or oil-pressure anomaly.
- Leaving the mixture at full rich during extended ground operations in warm weather, causing fouled spark plugs and rough running shortly after takeoff.
3. CFI PRO TIP
Have the student call out the critical items (mixture position, throttle setting, fuel pump, and expected instrument response) before moving any control during the first several starts. Verbalizing forces deliberate checklist use and gives you an immediate window into whether the student is thinking ahead or simply going through motions.
4. SAFETY SPOTLIGHT
NTSB accident data shows repeated instances of engine damage or in-flight power loss after pilots skipped or rushed the magneto and engine-instrument checks during runup. In several cases, a single magneto that was not fully grounded during shutdown was later misdiagnosed as “normal,” leading to rough running and eventual engine stoppage on departure.
5. DID YOU KNOW
For the fuel-injected Lycoming engines in later-model 172s, the POH hot-start procedure calls for the mixture to be at idle cutoff until the engine fires, then advanced to rich—doing this correctly prevents vapor lock that can otherwise ground the airplane for 30–60 minutes while the engine cools.
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