Airline MRO (maintenance, repair, and overhaul) technicians working in heavy check facilities — performing C-checks, D-checks, and major structural repairs on commercial aircraft — operate in large hangar environments where simultaneous aircraft operations, riveting, grinding, blasting, and test cell runs create a sustained high-noise environment across the entire shift. MRO facilities are general industry workplaces fully subject to OSHA 1910.95. The CDC estimates 22 million U.S. workers face hazardous occupational noise each year, and airline MRO technicians are a meaningful segment of that total.
Soundtrace provides automated audiometric testing, real-time noise monitoring, and HPD fit testing in a unified platform for employers across the industries where airline MRO technicians work.
Airline MRO facilities operating as general industry employers are fully subject to OSHA 1910.95. Unlike line maintenance at gates, MRO heavy check work involves extended hangar operations with multiple aircraft in work simultaneously — creating sustained ambient noise from many concurrent maintenance tasks. Riveting, abrasive blasting, grinding, and engine test operations in MRO hangar environments routinely produce TWAs above OSHA's action level.
Measured Noise Exposure Levels
| Operation | Typical Noise Level | OSHA Max Duration |
|---|---|---|
| Rivet gun (structural airframe work) | 105–118 dBA | Duration of riveting |
| Abrasive blasting (paint strip) | 100–115 dBA | Duration of blasting |
| Angle grinder (structural repair) | 95–105 dBA | Duration of use |
| Engine borescope run (test power) | 100–118 dBA | Duration of run |
| Sheet metal fabrication (in-shop) | 90–100 dBA | Duration of task |
| Pneumatic drill (skin removal) | 96–108 dBA | Duration of drilling |
| MRO hangar ambient (multiple aircraft) | 86–96 dBA | Full shift |
| Hydraulic test rig | 88–96 dBA | Duration of test |
OSHA Requirements
Under 29 CFR 1910.95, employers must implement a hearing conservation program when any worker's 8-hour TWA meets or exceeds 85 dBA. Required elements:
- Noise monitoring to establish documented TWA for each exposed worker
- Baseline audiogram within 6 months of first qualifying exposure (preceded by 14 hours of quiet)
- Annual audiograms compared to baseline for standard threshold shift (STS) detection
- Hearing protection provided at no cost in a variety of types and styles
- Annual training covering noise hazards, HPD use, and audiometric results
- Recordkeeping per 1910.95(m) — noise measurements, audiograms, training documentation
See: OSHA 1910.95: All 6 Elements Explained
Heavy Check Duration and Cumulative Shift Exposure
Unlike line maintenance where tasks are brief and aircraft exposure is intermittent, heavy check MRO work places technicians in the same hangar bay for full 8–12 hour shifts. An MRO technician on a D-check may spend weeks working on the same aircraft through sequential structural, systems, and interior tasks — accumulating consistent daily TWA exposure from a stable noise environment.
The combination of high-intensity task noise (riveting, blasting, grinding) and sustained hangar ambient noise from multiple concurrent aircraft in work creates a complex exposure profile requiring personal dosimetry for accurate characterization. Area monitoring at a fixed hangar location does not capture the variability between zones where different operations are underway simultaneously.
See: Aircraft Mechanic Hearing Loss and OSHA 1910.95: All 6 Elements Explained
Workers' Compensation Exposure
Occupational hearing loss WC claims are routinely filed years or decades after the causative exposure. Without a documented baseline audiogram, employers cannot establish what hearing the worker had at hire — making every dB of loss present at claim filing presumptively attributable to the current employer.
A complete audiometric record, maintained from day one of employment, is the only document that allows an employer to separate their noise exposure period from everything that came before and after.
See: Workers' Compensation for Occupational Hearing Loss and Noise-Induced Hearing Loss: The Employer's Complete Guide
Frequently Asked Questions
Yes, when their 8-hour TWA meets or exceeds 85 dBA. Many airline MRO technicians in active operations regularly meet or exceed this threshold. OSHA 1910.95 requires employers to enroll qualifying workers in a hearing conservation program including audiometric testing, hearing protection, training, and recordkeeping.
Noise-induced hearing loss (NIHL) is the primary occupational hearing condition. It typically presents first as a 4,000 Hz notch on audiometry before progressing to involve 3,000 and 6,000 Hz. The loss is permanent and irreversible once established, which is why early detection through annual audiometry is critical.
Yes. Occupational hearing loss is compensable in all U.S. states when a worker can establish that their hearing loss was caused or contributed to by workplace noise exposure. Claims are routinely filed years or decades after the exposure period. Employers with complete audiometric records and documented noise measurements are far better positioned to contest causation or support apportionment.
A compliant hearing conservation program includes noise monitoring to document TWA, baseline and annual audiograms, hearing protection at no cost, annual training, and complete recordkeeping. Individual HPD fit testing — measuring each worker's personal attenuation rating (PAR) — is the only method that verifies actual protection rather than assuming label NRR performance.
Hearing protection must provide adequate attenuation for the actual measured TWA. Individual fit testing verifies each worker's personal attenuation rating (PAR). At higher exposure levels — above 100 dBA — double protection combining earplug and earmuff is often required to achieve adequate attenuation.
In-house audiometric testing for aviation operations
Soundtrace delivers OSHA-compliant audiometric testing and noise monitoring for aviation employers — automated STS detection, 30-year cloud retention, and licensed audiologist supervision.
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