Fault Tree Analysis Worksheet

Fault Tree Analysis (FTA) works top-down: you start with the failure you want to prevent and trace backward through all possible events and conditions that could lead to it.

System / Process:

Date:

Analyst:

Reference #:

Review Team:

Next Review:

TOP EVENT — The undesired failure or outcome we are analyzing

Gate Legend

⊕OR Gate: Output occurs if ANY one input occurs

⊗AND Gate: Output occurs only if ALL inputs occur simultaneously

◇Basic Event: A root-level failure — no further breakdown needed

▭Intermediate Event: Can be broken down further into sub-causes

Fault Tree Diagram

Draw your tree below OR attach a separate diagram. Start from the top event and work downward, connecting events through OR/AND gates until you reach basic events.

[ Draw fault tree here — or attach a separate diagram sheet ]

Level 1 — Immediate Causes (directly leading to top event)

⊕ OR Gate — Any one of these can cause the top event

Cause A: Gate type below: ☐ OR ☐ AND ☐ Basic

Cause B: Gate type below: ☐ OR ☐ AND ☐ Basic

Cause C: Gate type below: ☐ OR ☐ AND ☐ Basic

Cause D: Gate type below: ☐ OR ☐ AND ☐ Basic

Level 2 — Sub-Causes (expand the most critical Level 1 cause)

▭ Expanding: Cause A (write the name above here)

Sub-cause A1: ☐ Basic Event ☐ Expand further

Sub-cause A2: ☐ Basic Event ☐ Expand further

Sub-cause A3: ☐ Basic Event ☐ Expand further

Sub-cause A4: ☐ Basic Event ☐ Expand further

Corrective Actions — Address the Basic Events

#	Basic Event (Root Cause)	Corrective Action	Owner	Due Date
1
2
3
4