WARNING LETTER
Linemaster Switch Corporation
MARCS-CMS 730215 —
May 27, 2026
Delivery Method:
VIA Electronic Mail
Product:
Medical Devices
Recipient:
Recipient Name
Joseph Carlone Jr.
Recipient Title
President and CEO
Linemaster Switch Corporation
29 Plaine Hill Road
Woodstock
,
CT
06281
United States
(b)(6), (b)(7)(C)
Issuing Office:
Center for Devices and Radiological Health
United States
WARNING LETTER
CMS #730215
May 27, 2026
Dear Mr. Carlone:
During an inspection of your firm located in Woodstock, CT from February 4, 2026, through March 6, 2026, an investigator from the United States Food and Drug Administration (FDA) determined that your firm manufactures foot pedal accessories for medical devices, including Class II foot pedal controls used with Class IV medical lasers. Under section 201(h) of the Federal Food, Drug, and Cosmetic Act (the Act), 21 U.S.C. § 321(h), these products are devices because they are intended for use in the diagnosis of disease or other conditions or in the cure, mitigation, treatment, or prevention of disease, or to affect the structure or any function of the body.
Quality Management System Regulation Violation(s)
This inspection revealed that these devices are adulterated within the meaning of section 501(h) of the Act, 21 U.S.C. § 351(h), in that the methods used in, or the facilities or controls used for, their manufacture, packing, storage, or installation are not in conformity with the current good manufacturing practice requirements of the Quality Management System Regulation found at Title 21,
Code of Federal Regulations
(CFR), Part 820.
We received your response dated March 30, 2026, concerning our investigator’s observations noted on the Form FDA 483 (FDA 483), List of Inspectional Observations, that was issued to your firm. We address this response below, in relation to each of the noted violations. These violations include, but are not limited to, the following:
1. Failure to perform rework in accordance with documented procedures that take into account the potential adverse effect of the rework on the product, as required by ISO 13485:2016, Clause 8.3.4.
Specifically, your firm did not implement their procedure, Q 006 Rev D3, Nonconforming Material Control, dated October 14, 2025. For example:
Section 7.6 of the procedure states "Rework and repair instructions shall be documented on the MRR or a Nonconforming Material Rework/Repair Request form Q6-12 with specific Manufacturing and Inspection Instructions recorded." Rework was not documented when nonconforming units were identified. During the manufacture of Job
(b)(4)
, the Manufacturing Manager explained that Job
(b)(4)
, which consisted of
(b)(4)
units of
(b)(4)
(part number
(b)(4)
) foot pedals had nonconforming product and was being reworked because after calibration, the assembler had failed to
(b)(4)
screws. The supervisor had the assembler perform rework to apply torque and recalibrate all
(b)(4)
units, and this rework was not being documented.
We are aware that inadequate calibration of your foot pedals may result in unintended laser activation or inadequate laser power delivery.
The adequacy of your response cannot be determined at this time. We understand that you plan to review and revise your reprocessing and rework procedures to ensure documentation is appropriate for any lots that do not meet specifications. You also plan to do a retrospective review of reworked lots and assess whether any remedial action is needed. However, you have not provided a timeline for when this work will be completed or any revised documents. In response to this Warning Letter, please provide your revised procedures as well as a summary of the retrospective review when complete and describe any corrective actions that may be required.
2. Failure to document one or more processes for risk management in product realization, as required by ISO 13485:2016, Clause 7.1.
Specifically,
a. Your firm failed to implement Risk Management procedure TM-112, Rev D Section 5.3.2, which states "Process FMEA's are created to assess the highest risk in processing and action is taken to reduce the risk", in that you failed to have a Process FMEA for foot pedal
(b)(4)
(part number
(b)(4)
), an accessory device used to control Class IV medical lasers.
b. Your firm's Risk Management procedure TM-112 does not define how risk management activities are performed and documented, who is responsible for conducting and approving risk management activities, when risk management documentation must be updated, and how post-market feedback data (including complaints, adverse events, and recalls) is incorporated into risk management.
The adequacy of your response cannot be determined at this time. We understand that you plan to update your risk management procedure, perform a retrospective assessment of available post-market and internal quality data and then create or update your current risk management files. However, you have not provided a timeline for when this work will be completed or any revised documents. In response to this Warning Letter please provide updated risk documents as well as a summary of your retrospective review when complete and describe any corrective actions that may be required.
3. Failure to document corrective action procedures to define the requirements for determining the causes of nonconformities and reviewing the effectiveness of corrective action taken, as required by ISO 13485: 2016: Clause 8.5.2.
Specifically, Nonconforming Material Report Procedure Q 006 Rev D3, section 9.1, which requires that Customer Requests for Corrective Action shall be investigated, and a corrective action plan be developed, was not implemented.
For example, SCAR-00014, dated November 14, 2023, was opened because 6 foot pedals,
(b)(4)
, failed the calibration verification test at the customer’s facility. This SCAR was not investigated as required by your procedure. Your SCAR response to the customer on January 26, 2024, shows Root Cause [BLANK] and Corrective Action "NA".
The adequacy of your response cannot be determined at this time. We understand that you plan on revising procedures governing SCAR and customer corrective action responses. We also understand that you plan to do a retrospective review of customer-originated corrective action requests and similar calibration-related nonconformities. However, you have not provided a timeline for when this work will be completed or any revised documents. In response to this Warning Letter, please provide your revised procedures as well as a summary of the retrospective review when complete and describe any corrective actions that may be required.
4. Failure to document the requirements for the work environment and the procedures to monitor and control the work environment, when conditions for the work environment can have an adverse effect on product quality, as required by ISO 13485:2016, Clause 6.4.1.
Specifically, your firm does not have procedures or controls to monitor the work environment that can have an adverse effect on product quality. Your firm identified an issue with
(b)(4)
, which is the unintended change in a sensor’s output due to temperature fluctuations, causing measurement inaccuracy over time in your Request for Engineering Assistance (REA) #20130763, dated September 26, 2013. However, you have not developed any procedures or put in place any controls to monitor the temperature to demonstrate that these devices maintain accurate calibration under temperature variations. The only control put into place was implementation of a
(b)(4)
in the device firmware.
The adequacy of your response cannot be determined at this time. We understand that you plan to validate
(b)(4)
across relevant temperature conditions and also plan to establish any needed facility, equipment, or process changes required to maintain the defined work environment during calibration. However, you have not provided a timeline for when this work will be completed or provided any protocols or documents to confirm this work is being done. In response to this Warning Letter please provide documentation of your completed successful validation.
5. Failure to document procedures for the validation of the application of computer software used for the monitoring and measurement of requirements, as required by ISO 13485:2016, Clause 7.6
Specifically,
a. Your firm's Monitor Program
(b)(4)
software, used in calibration procedure TM-118 Rev C and quality test procedure QTP
(b)(4)
Rev G for calibration and testing of
(b)(4)
, foot pedal accessory devices, was not adequately validated. For example, the validation, TM-117 Rev A, September 26, 2013, did not include:
Raw data from validation testing
Pass/fail criteria or results
Statistical analysis or sample size rationale
Verification that the software accurately measures output values and reliably detects nonconforming devices
During FDA’s inspection our Investigator observed the testing setup of
(b)(4)
. He observed there were multiple software COM port errors in both in-process assembly and final product testing areas. Firm personnel described these as routine and these errors were not investigated. From 2023 - 2025, we observed that a total of
(b)(4)
units passed Linemaster's calibration testing using
(b)(4)
but were subsequently returned because they failed customer calibration testing.
b. Your firm has not adequately validated the
(b)(4)
to prevent calibration drift of the
(b)(4)
, foot pedal accessory. As noted above, your firm identified an issue with
(b)(4)
in your Request for Engineering Assistance (REA) #20130763, dated September 26, 2013. However, the referenced validation document, TM-83 Rev A "997-P46 Firmware Validation Product:
(b)(4)
," did not include:
Testing at multiple temperatures or temperature ranges
Correlation between temperature and sensor output
Demonstration that
(b)(4)
maintains calibration accuracy across temperature variations
Raw data showing
(b)(4)
performance
Statistical analysis of
(b)(4)
effectiveness
Pass/fail criteria specific to
(b)(4)
performance
Temperature cycling or
(b)(4)
stress testing
Comparison of calibrated vs. uncalibrated performance across temperatures
The adequacy of your response cannot be determined at this time. We understand that you plan to revalidate the
(b)(4)
software as well as assess whether any prior product disposition or calibration decisions require additional review based on software validation findings. However, you have not provided a timeline for when this work will be completed or provided any protocols or documents to confirm this work is being done. In response to this Warning Letter, please confirm when this revalidation will be completed and whether any additional product disposition is required after your review is completed.
A follow up inspection will be required to ensure that corrections and/or corrective actions are adequate.
Your firm should take prompt action to address any violations identified in this letter. Failure to adequately address this matter may result in regulatory action being initiated by the FDA without further notice. These actions include, but are not limited to, seizure, injunction, and civil money penalties.
Other federal agencies may take your compliance with the FD&C Act and its implementing regulations into account when considering the award of federal contracts. Additionally, should FDA determine that you have Quality Management System Regulation violations that are reasonably related to premarket approval applications for Class III devices, such devices will not be approved until the violations have been addressed. Should FDA determine that your devices or facilities do not meet the requirements of the Act, requests for Certificates to Foreign Governments (CFG) may not be granted.
Please notify this office in writing within fifteen business days from the date you receive this letter of the specific steps your firm has taken to address the noted violations, as well as an explanation of how your firm plans to prevent these violations, or similar violations, from occurring again. Include documentation of the corrections and/or corrective actions (which must address systemic problems) that your firm has taken. If your firm’s planned corrections and/or corrective actions will occur over time, please include a timetable for implementation of those activities. If corrections and/or corrective actions cannot be completed within fifteen business days, state the reason for the delay and the time within which these activities will be completed. Your firm’s response should be comprehensive and address any violations included in this Warning Letter. If you believe that your products are not in violation of the FD&C Act, include your reasoning and any supporting information for our consideration as part of your response.
Your firm’s response should be sent via email to Gina Brackett, Assistant Director at CDRHEnforcement@fda.hhs.gov. Please include in the subject line, “CMS Case #730215” when replying. If you have any questions about the contents of this letter, please contact: Karen Archdeacon, Compliance Officer at karen.archdeacon@fda.hhs.gov.
Finally, you should know that this letter is not intended to be an all-inclusive list of the violations at your firm’s facility. It is your firm’s responsibility to ensure compliance with applicable laws and regulations administered by FDA. The specific violations noted in this letter and in the Inspectional Observations, FDA 483, issued at the close of the inspection may be symptomatic of serious problems in your firm’s manufacturing and quality management systems. Your firm should investigate and determine the causes of any violations and take prompt actions to address any violations and bring the products into compliance.
Sincerely,
/S/
Barbara C. Marsden
Director
Office of Regulatory Programs
Office of Product Evaluation and Quality
Center for Devices and Radiological Health
Cc: Edward Ursillo, Director of Quality Assurance,
(b)(6), (b)(7)(C)
Content current as of:
07/22/2026
Regulated Product(s)
Medical Devices