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Publication Number: FHWA-HRT-07-040
Date: October 2011

 

Falling Weight Deflectometer Calibration Center and Operational Improvements: Redevelopment of The Calibration Protocol and Equipment

APPENDIX D. QA REVIEWS

The purpose of a QA review is to achieve consistency of calibrations among centers. When the protocol is done correctly, the final gain factors for an FWD will be accurate within ±0.3 percent regardless of which center performs the calibration. QA reviews should be performed annually to ensure that the center is achieving the quality standards. In addition, the QA review provides the center with the most current information about the protocol.

Three people are needed to perform a QA review: the FWD calibration operator, an FWD operator, and the independent QA reviewer. Table 11 lists the roles and responsibilities for each person involved in the review.

Table 11. Roles and responsibilities during QA review.
Personnel Role Definition
FWD calibration operator Independently performs an FWD calibration in accordance with the most recent calibration protocol.
FWD operator Runs the FWD during the calibration.
QA reviewer Observes the FWD calibration and assesses the proficiency of the calibration operator.

This appendix assumes a single FWD calibration operator is being reviewed, but multiple people may be certified in a single QA review. One day should be scheduled for each FWD calibration operator. While training is not part of the QA review, if a new operator needs to be trained during the same visit, up to an additional 2 days should be scheduled for that.

Prior to the review, the calibration operator is provided with a pre-QA review questionnaire to assure a smooth and efficient review (see figure 43). An operator review form (see figure 44) and a facilities review form (see figure 45) are used during the review. Copies of these forms should also be sent out before the review. The purpose of each document is as follows:

In order for the QA review to be efficient, it is important that the FWD is in good working condition. It is not required that the FWD passes the calibration in order for the calibration center operator to demonstrate his/her proficiency and be certified. However, if the FWD is not working properly, it may not be possible to complete the review process.

REVIEW PROCESS

At the beginning of the review, the calibration operator, FWD operator, and QA reviewer meet to discuss the anticipated flow of the review process. This provides an opportunity to ask questions about the review, the calibration protocol, or the software and equipment. Problems or questions that have come up during the previous year can be reviewed and discussed. During this meeting, the QA reviewer should provide information about changes in the protocol or the software since the last review.

As part of the review, the QA reviewer will copy the last year of FWD calibration results from the calibration computer to a CD, a thumb drive, or a portable hard drive. This semiautomated process takes 15–45 min once it is started depending on how many files need to be copied. It can be done while the QA review meeting is taking place. After the files are copied, the QA reviewer will update the FWD calibration software and provide a backup copy of the updated software for the calibration operator.

Facility Review

A review of the facility and the equipment determines compliance with the FWD calibration protocol. This assures that the equipment conforms to the protocol and that it is in good working condition.

The QA reviewer checks that the equipment being used is compliant with the calibration protocol, the serial numbered equipment are correct, the reference devices are up to date on their calibrations, and the facility is able to perform FWD calibrations without electromagnetic interference or significant temperature changes during a typical FWD calibration. A checklist assists the reviewer by providing information on the important observation points. It is used as a record of the items reviewed.

Operator Review

The calibration operator is reviewed to assure that the protocol is being performed correctly. The calibration operator demonstrates proficiency with the protocol by calibrating an FWD. Three levels of operator compliance have been defined in table 12.

A checklist guides the QA reviewer through the important observation points. This includes the setup procedure in the WinFWDCal software, deflection sensor calibration, load cell calibration, and documentation and certification of the FWD calibration.

Table 12. Calibration operator compliance levels for QA review.
Compliance Level Definition
Fully compliant Operator fully understands and demonstrates sound implementation of the calibration protocol and uses the calibration equipment and software appropriately.
Partially compliant Operator fully understands the calibration protocol. Some necessary changes in equipment, software use, and/or implementation of the calibration protocol may be required.
Noncompliant Operator does not demonstrate an adequate understanding of the calibration protocol or its implementation.

Upon completion of the FWD calibration, the calibration operator and QA reviewer meet to discuss the review process and communicate any needed modifications. The FWD operator should be included in the meeting if the QA reviewer feels that this would improve the quality of future calibrations. During the meeting, the QA reviewer informs the calibration operator of the compliance level. When the review is passed, the operator is issued a certificate of compliance. A sample certificate is provided in figure 46.

A written report documenting the QA visit should be created as soon as possible after the visit, preferably within 2 weeks. The certificate of compliance is valid for 15 months, but the next QA visit must be scheduled within 12 months. This allows some flexibility in scheduling but ensures communication within 1 year.

Because AMRL took over responsibility for the QA visits in late 2010, it can be expected that some changes in procedures and checklists will occur.

Figure 43. Illustration. Pre-QA review questionnaire. This figure shows the questions asked of the falling weight deflectometer (FWD) calibration center prior to a quality assurance visit. The questionnaire asks the center to list how many FWD calibrations have been completed. It also asks for suggestions, problems, and needs since the last quality assurance (QA) visit.

Figure 43. Illustration. Pre-QA review questionnaire.

Figure 44. Illustration. Calibration operator QA review form. This multipage questionnaire provides a series of check boxes with space for notes for review of a falling weight deflectometer (FWD) calibration center operator during a quality assurance (QA) visit. Each check box is associated with a requirement or suggestion for FWD calibration. The form has sections on facilities and FWD setup, calibration setup, deflection sensor calibration, load cell calibration, and documentation and certification. It also provides a place to write the name of the operator and the center and the name and signature of the QA reviewer.

Figure 44. Illustration. Calibration operator QA review form.

Figure 44 (continued). Illustration. Calibration operator QA review form.

Figure 44 (continued). Illustration. Calibration operator QA review form.

Figure 44 (continued). Illustration. Calibration operator QA review form.

Figure 44 (continued). Illustration. Calibration operator QA review form.

Figure 44 (continued). Illustration. Calibration operator QA review form.

Figure 44 (continued). Illustration. Calibration operator QA review form.

Figure 44 (continued). Illustration. Calibration operator QA review form.

Figure 44 (continued). Illustration. Calibration operator QA review form.

Figure 45. Illustration. Center facilities QA review form. This multipage questionnaire provides a series of check boxes with space for notes for review of a falling weight deflectometer (FWD) calibration center facility during a quality assurance (QA) visit. Each check box is associated with a requirement or suggestion for FWD calibration. The form has sections on facility and equipment. It also provides a place to write the name of the calibration center and the name and signature of the QA reviewer.

Figure 45. Illustration. Center facilities QA review form.

Figure 45 (continued). Illustration. Center facilities QA review form.

Figure 45 (continued). Illustration. Center facilities QA review form.

Figure 45 (continued). Illustration. Center facilities QA review form.

Figure 45 (continued). Illustration. Center facilities QA review form.

Figure 46. Illustration. Center operator certificate of compliance. This figure shows a typical falling weight deflectometer center operator certificate of compliance. It has the name of the certified operator, the name of the calibration center, and a place for a signature of the quality assurance reviewer. The certificate indicates that it is valid for 15 months after issuance.

Figure 46. Illustration. Center operator certificate of compliance.


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The Federal Highway Administration (FHWA) is a part of the U.S. Department of Transportation and is headquartered in Washington, D.C., with field offices across the United States. is a major agency of the U.S. Department of Transportation (DOT). Provide leadership and technology for the delivery of long life pavements that meet our customers needs and are safe, cost effective, and can be effectively maintained. Federal Highway Administration's (FHWA) R&T Web site portal, which provides access to or information about the Agency’s R&T program, projects, partnerships, publications, and results.
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