> ## Documentation Index
> Fetch the complete documentation index at: https://www.narev.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Engine start — part 3

> Engine start — part 3: conditions, actions and checks for the Boeing 737-800.

Use this procedure when its prerequisites apply. Confirm each required aircraft state before acknowledging the corresponding checklist item.

## General

Start **engine 2**, then **engine 1**. Begin engine 1 start only after engine 2 is stable. Complete the applicable preceding procedures and establish the assigned start-readiness and air-supply conditions before selecting GRD.

### Start controls

**Caution:** The start lever controls fuel admission. `SET_THROTTLE` controls thrust levers and is not the control for start-lever IDLE.

At **25% N2**, move the associated start lever to IDLE. Observe the N2 condition during the current start; do not act from an old sample or use thrust-lever percentage as N2.

At **56% N2**, **verify** that the associated engine start switch has returned to OFF. Do not select `ENG1_START_OFF` or `ENG2_START_OFF` merely to satisfy this verification. N2 reaching 56% does not prove switch return or starter-valve closure.

Verify the associated **START VALVE OPEN** indication is extinguished, then announce starter cutout. Keep switch return, valve indication, cutout announcement and engine stability as separate requirements.

### Engine 2 stable

Before the engine 1 start sequence, verify engine 2 stable against the assigned criteria. The stable condition applies to the entire engine 1 start sequence, including the announcement and GRD selection, even where later item text does not repeat it. The checklist supplies no numerical stability band or dwell time.

### Completion and continuation

Continue through all three pages. The source transitions connect part 1 to part 2 and part 2 to part 3; they do not override an item condition. After part 3 and the applicable readiness checks are complete, select Before Taxi, [Before Taxi](https://www.narev.ai/docs/irl-gym/aircraft/procedures/before-taxi-1.md).

If required start indications or instructions are unavailable, do not advance through the normal sequence. Use the assigned supervisory or non-normal start procedure. This chapter does not specify hot-start, hung-start, no-lightoff, starter-limit or abnormal-start recovery actions.

### 1. Engine 1 at 56% N2: Engine 1 start switch OFF — **Verify**

**Condition:** Engine 1 at 56% N2.

When engine 1 N2 reaches 56%, verify that engine 1 start switch has returned to OFF. This is a verification item; do not select OFF merely to obtain the required indication.

> **Checks and evidence**
>
> **When:** Engine 1 at 56% N2.
>
> **Expected response:** Verify
>
> **Verification:** The 56% N2 event and the engine 1 start-switch OFF indication are observed independently.

### 2. START 1 VALVE OPEN — **Extinguished**

Verify START 1 VALVE OPEN is extinguished following the engine 1 start-switch OFF verification.

> **Checks and evidence**
>
> **Expected response:** Extinguished
>
> **Verification:** The powered, valid START 1 VALVE OPEN indication is extinguished.

### 3. Starter 1 cutout — **Announce**

After the preceding switch and valve indications have been verified, announce starter 1 cutout through the assigned communication channel.

> **Checks and evidence**
>
> **Expected response:** Announce
>
> **Verification:** Starter 1 cutout is supported by the preceding checks, and the cutout announcement has been transmitted.

## Continue after this procedure

No explicit source transition is declared. Select the next applicable procedure after the required completion and entry conditions are established.


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