Hot Start Procedures

Definition

A hot start occurs when an aircraft engine—typically a turbine or jet engine—experiences abnormally high exhaust gas temperatures (EGT) during engine start-up, potentially exceeding manufacturer limits. This can lead to engine damage if not immediately addressed. A hot start usually results from early fuel introduction, slow rotation (N2), or insufficient airflow during light-off.

Purpose of Hot Start Procedures

Detect and respond to an abnormal engine start condition
Protect engine components from thermal damage
Allow for safe recovery and restart attempts after a hot start
Ensure compliance with manufacturer and regulatory procedures

Common Causes of a Hot Start

Cause	Description
Premature fuel introduction	Fuel introduced before sufficient airflow (N2) is established
Weak starter performance	Starter fails to accelerate core fast enough to cool combustion
Hot ambient conditions	Reduce the cooling effect of air and raise baseline EGT
Residual heat	Recent shutdown may leave engine components already hot
Ignition system faults	Improper timing or delayed combustion may spike temperatures

Hot Start Symptoms

Indicator	Observation
EGT rise	Rapid, steep increase beyond limits during start
N2/N1 lag	Rotor speeds remain low or slow to stabilize
Smoke/smell	May be visible from exhaust in severe cases
Warnings	Engine monitoring system alerts or redlining gauges

Immediate Hot Start Procedure (Typical Jet)

🚨 Memory Actions – Abort the Start

Fuel lever/Cutoff switch — OFF
Ignition switch — OFF
Starter/Motor — ON (if required to cool engine)
Motor for 20–30 seconds or per POH/AFM
Monitor EGT drop to safe levels
Allow cooldown, then assess whether a re-attempt is permitted

Always refer to the Aircraft Flight Manual (AFM) or QRH (Quick Reference Handbook) for aircraft-specific procedures.

Phraseology (If Coordinated with Ground Crew)

“Abort start, hot start on engine two.”
“Cutting fuel, request continued motoring.”
“Stand by, engine cooling in progress.”

Prevention Tips

✅ Ensure starter air source is strong (APU or GPU)
✅ Wait for adequate N2 RPM before introducing fuel
✅ Monitor EGT closely during light-off
✅ Do not rush the sequence—follow the checklist exactly
✅ Use battery or APU voltage checks to verify starting power

If a Hot Start Occurs

Log the event in the technical logbook
Notify maintenance personnel immediately
The engine may require borescope inspection or trend monitoring
Do not attempt another start unless specifically approved

Difference: Hot Start vs. Hung Start

Type	Description	Action
Hot Start	EGT exceeds limits	Cut fuel immediately
Hung Start	N2 fails to reach idle RPM	Abort start and cool down

Tips for Pilots

Know the EGT limits and start envelope for your aircraft
Practice with simulated malfunctions in LearnATC or flight training devices
Don’t hesitate to abort early—waiting often makes it worse
Re-brief engine start actions before every first start of the day