Overview: Why AMS 2432 Rev G Matters
AMS 2432, the SAE specification for computer-monitored shot peening, underwent its most significant revision in over a decade with the release of Revision G. This update directly affects aerospace manufacturers, Tier 1 suppliers, and Nadcap-accredited shot peening facilities that process critical rotating and structural components for aerospace primes including Boeing, Airbus, GE Aviation, Pratt & Whitney, and Rolls-Royce.
The revision introduces enhanced data acquisition mandates, tightened saturation curve documentation requirements, and new sub-tier supplier controls that were not present in Rev F. Facilities that continue operating under Rev F processes without updating their documentation risk non-conformances during Nadcap AC7117 audits and potential purchase order non-compliance.
Key Changes from Rev F to Rev G
1. Continuous Process Parameter Logging (§7.3)
The most operationally significant change in Rev G is the expansion of mandatory continuously logged parameters. Under Rev F, many facilities logged parameters at start-of-run and end-of-run only. Rev G now requires continuous real-time acquisition throughout each production run for:
- Nozzle air pressure — logged at minimum every 30 seconds, with upper and lower alarm limits defined in the Equipment Qualification Record (EQR)
- Part rotation speed (RPM or surface speed, as applicable) — continuously monitored with tolerance band per EQR
- Nozzle traverse speed — for automated traverse systems; logged continuously
- Wheel speed (for centrifugal wheel machines) — RPM logged with ±5% tolerance band
- Media flow rate — for systems equipped with flow meters; logged with alarm limits
- Exposure time per zone — for indexed or multi-position part fixtures
Facilities must verify their data acquisition systems (DAS) have sufficient logging frequency and storage capacity. The specification does not prescribe a DAS vendor or software platform, but the system must produce a retrievable, tamper-evident record associated with each production traveler/lot.
2. Saturation Curve Documentation Requirements (§8.2)
Rev G tightens the content requirements for saturation curves stored in the EQR. The curve record must now include:
- Machine ID and nozzle/wheel position identifier
- Date of qualification and name of qualifying engineer/technician
- All raw arc height data points (minimum 4 exposure times per J443)
- The plotted saturation curve with the saturation point and intensity value clearly identified
- Media type, lot number, size designation, and hardness range per applicable AMS media spec
- All process parameters at which the curve was established (pressure, standoff, angle, part speed, flow rate)
- The ±15% production tolerance band plotted on the same chart
Under Rev F, many facilities maintained curves as simple tables of arc height vs. time without the full parameter documentation. Rev G-compliant curve packages require a more comprehensive single document that allows an auditor to fully reconstruct the qualified process setup from the record alone.
3. Production Verification Strip Frequency (§9.1)
Rev G clarifies and in some cases increases the frequency of production Almen strip verification. The new requirements are:
| Production Run Duration | Minimum Strip Frequency | Strip Placement |
|---|---|---|
| All runs | Start-of-run strip required | Per qualified fixture position |
| Runs > 4 hours | Mid-run strip required | Same fixture position as start strip |
| Runs > 8 hours | Every 4 hours thereafter | Rotating through fixture positions |
| End of each shift | End-of-run strip required | Per qualified fixture position |
Strips must be retained with the traveler for the duration of the part's record retention requirement. The arc height, strip type, machine ID, nozzle ID, operator ID, date, and time must be recorded on the traveler or in a linked electronic record.
4. Process Change Control Procedure (§10)
Rev G introduces a formal Process Change Control (PCC) section that was absent in Rev F. This section defines what constitutes a "process change" requiring requalification and what constitutes a "minor adjustment" that may be made within the EQR tolerance band without requalification. Facilities must now maintain a written PCC procedure that addresses:
- Defined tolerance bands for each process parameter (within which adjustments are allowed without requalification)
- A change authorization workflow requiring engineering or quality sign-off before any change outside tolerance bands
- A requalification trigger matrix listing specific conditions requiring a new saturation curve
- A customer notification procedure for changes that affect form, fit, or function (per AS9100 change management)
5. Sub-Tier Media Supplier Controls (§6.4)
Rev G adds explicit sub-tier supplier control requirements for peening media suppliers that were previously implied but not specified. The new language requires:
- An approved media supplier list (ASL) maintained by the facility, with documented approval criteria
- Incoming verification of each media lot against the applicable AMS specification (AMS 2431/2434/2435/2437/2438)
- A media lot traceability system linking each production run traveler to the specific media lot(s) used
- Media supplier audit or survey records at a defined interval (the spec recommends at least every 3 years)
Documentation Update Checklist
Use the following checklist to bring existing Rev F process documentation into Rev G compliance:
| Document | Rev F Status | Rev G Requirement | Action |
|---|---|---|---|
| Equipment Qualification Record (EQR) | Partial parameter list | Full continuous parameter set | Update EQR template; add §7.3 parameters |
| Saturation Curve Packages | Arc height table only | Full curve + parameter documentation | Re-document or rerun curves |
| Process Instructions / Work Orders | Start/end parameter check | Continuous DAS logging reference | Add DAS reference and alarm limit table |
| Shop Traveler | Strip arc height + operator | Strip arc height + time + machine ID + nozzle ID | Update traveler fields |
| Process Change Control Procedure | Not required (Rev F) | Formal written PCC procedure | Create new procedure per §10 |
| Media Supplier ASL | Not required (Rev F) | Formal ASL with approval criteria | Create ASL; document incoming verification |
| Production Strip Log | Start-of-run only | Mid-run and end-of-run per §9.1 | Update strip frequency per table above |
Data Acquisition System (DAS) Requirements
If your facility's current DAS was configured for Rev F compliance, it likely needs to be upgraded or reconfigured. Key DAS requirements under Rev G include:
- Logging frequency: Minimum 30-second intervals for pressure; event-triggered for alarms. Some customers (notably GE Aviation) require 10-second intervals per their supplemental requirements.
- Alarm logging: Any parameter exceedance must be flagged with timestamp in the production record. The run disposition (accept/reject/rework) must be documented when an alarm occurs.
- Record format: Records must be exportable in a non-proprietary format (PDF, CSV, or equivalent) to support customer and auditor access. Proprietary binary formats are not acceptable without a viewer tool.
- Record retention: DAS records must be retained per the greater of: the part's drawing-specified retention period, 10 years, or the customer's contractual record retention requirement.
- Tamper evidence: The system must either use locked records (no editing after sign-off) or maintain an audit trail of any post-run edits with user ID, timestamp, and reason.
Nadcap AC7117 Audit Implications
Nadcap auditors conducting AC7117 audits at facilities claiming AMS 2432 compliance will specifically verify Rev G requirements starting from the revision's effective date. Expect auditor scrutiny on:
- Objective evidence of continuous parameter logging from a recent production run
- Completeness of saturation curve packages per new §8.2 content requirements
- Existence and implementation of the PCC procedure
- Media lot traceability from traveler back to media C of C
- Production strip frequency compliance for long runs (>4 hours)
Facilities that received their most recent Nadcap accreditation under Rev F should proactively schedule an internal audit against Rev G requirements before their next surveillance or re-accreditation audit.
Summary
AMS 2432 Rev G represents a meaningful tightening of process control and documentation requirements for computer-monitored shot peening. The changes are concentrated in four areas: continuous DAS logging, saturation curve documentation completeness, production strip frequency, and formal process change control. Facilities with robust existing quality management systems will find most requirements achievable with documentation updates rather than capital investment — the exception being DAS upgrades for facilities whose current systems only support start/end-of-run logging.
Begin your transition by auditing existing EQR packages and shop travelers against the Rev G checklist above, then develop the new Process Change Control procedure as a standalone quality document linked to your existing process instructions.