Expands the main menu


Audit Reports

  • Image
Report Number:
Report Type:
Audit Reports
Category: Technology, Delivery / Mail Processing

Repair and Maintenance of Package Sorting Machines at Delivery Units


In November 2014, the Postal Service deployed the Automated Delivery Unit Sorter (ADUS), which automated the sorting of smaller packages in delivery units and small processing and distribution centers. Further, in 2021, as part of the 10-year Delivering for America Plan, the Postal Service kept its commitment to accelerate investments in new package sorting equipment to delivery units and rolled out the Small Delivery Unit Sorter (SDUS). According to the Postal Service, these machines process packages 12 times faster than manual sorting. However, this productivity can be affected by equipment breakdowns.
Analysis of data from October 1, 2021, through December 31, 2022, shows that 45 of 122 (or about 36.9 percent) ADUS and SDUS machines have downtime that is greater than the average for all delivery unit ADUS and SDUS machines.

What We Do

The objective of this audit was to evaluate how maintenance is performed on package sorting equipment within delivery units and determine the impact on machine downtime.

What We Found

The Postal Service did not properly perform maintenance on package sorting equipment at three of the four delivery units reviewed to ensure optimum performance and appropriate asset life. However, we did not find a direct correlation between lack of maintenance and machine downtime at the selected delivery units.

We found the main cause of machine downtime at the selected units was due to personnel improperly using the emergency stop button whenever they needed to stop the machine. Further, delivery unit personnel did not properly induct mail on the ADUS machine at both Toms River Main Post Office and Paschall Station. The improper operation of the package sorting machines was due to insufficient training of personnel, made worse by an overall insufficient number of personnel to optimally staff the machines.


We provided nine total recommendations, five to address issues with inconsistent maintenance and improper operation of package sorting equipment, one to address not entering the deployment of a machine into required data systems, and three to address ineffective communication between operation and maintenance personnel.

Report Recommendations

# Recommendation Status Value Management Response OIG Response USPS Proposed Resolution

Instruct the Philadelphia P&DC to
perform and confirm completion of all required preventive maintenance on a consistent basis on the ADUS at Paschall Station

Closed $0 Agree

Provide ongoing informal training for
SDUS clerks by a subject matter expert or on-the-job trainer at the unit, where the trainer can instruct personnel in the
proper procedures for daily preventive maintenance for the SDUS.

Open $0 Agree

widely distribute - to include delivery units with package sorting equipment - a policy on the proper usage of emergency stop buttons.

Closed $0 Agree

Develop a plan to provide the delivery units visited with the resources needed to effectively run their operations, and in the interim, develop a plan to best use the resources on hand, taking into account optimal start times for machines based on employee availability and mail volume.

Closed $0 Agree

Require anyone assigned to operate package sorting machines within delivery units to receive training on the proper operation of that machine - including start up and shut down procedures and inducting mail onto the machine.

Closed $0 Agree

Complete the ongoing project to effectively track and document changes, including the deployment of new equipment across the Postal Service network, to ensure that all machines are entered into eMARS timely.

Open $0 Agree

Consider directing local management at the four delivery units visited to develop and maintain a method of communication between operations and maintenance personnel to improve transfer of knowledge of identified issues and solutions.

Open $0 Agree

Instruct local management at the four delivery units visited to improve communication - to include the use of huddle boards - and oversight of package sorting machine performance to increase efficiency of the operation.

Closed $0 Agree

Periodically reinforce to personnel at the four delivery units visited the need to open a MTSC ticket with complete and accurate information of identified maintenance issues, when required.

Closed $0 Agree