Auto - Report writing

Introduction

As technicians you may be called on to produce a report for a customer. Also, if you are involved in research of some kind it is important to be able to present results in a professional way. The following sections describe the main headings that a report will often need to contain together with an example report based on the performance testing of a vehicle alternator. Laying out results in a standard format is the best way to ensure that all the important and required aspects of the test have been covered. Keep in mind that the report should convey clearly to another person what has been done. Further, a ‘qualified’ person should be able to extract enough information to be able to repeat the test – and check your findings! Use clear simple language remembering that in some cases the intended audience may not be as technically competent as you are.

Main headings of a report

The following suggestions for the headings of a professional report will cover most requirements but can of course be added to or subtracted from if necessary. After each heading I have included brief notes on what should be included.

Contents

If the report is more than about five pages, a list of contents with page numbers will help the reader find his/her way through it.

Introduction

Explain the purpose of what has been done and set the general scene.

Test criteria

Define the limits within which the test was carried out. For example, temperature range or speed settings.

Facilities/resources

State or describe what equipment was used. For example: ‘A “Revitup” engine dynamometer, model number C3PO was used for the consumption test’.

Test procedures

Explain here exactly what was done to gain the results. In this part of the report it is very important not to leave out any details.

Measured results

Present the results in a way that is easy to interpret. A simple table of figures may be appropriate. If the trend of the results or a comparison is important, a graph may be better. Pictures of results or oscilloscope waveforms may be needed. If necessary a very complex table of results from which you draw out a few key figures, could be presented as an appendix. You should also note the accuracy of any figures presented ( 0.5% for example).

Analysis of results

This is the part where you should comment on the results obtained. For example, if say a fuel consumption test was carried out on two vehicles, a graph comparing one result to the other may be appropriate. Comments should be added if necessary, such as any anomaly that could have affected the results (change of wind direction for example).

Conclusions/comments/observations

Note here any further tests that may be necessary. Conclude that device X does perform better than device Y – if it did! If appropriate, add observations such as how device Y performed better under the set conditions, but under other circumstances the results could have been different. Comment on the method used if necessary.

Forecast

If necessary comment on how the ‘item’ tested will continue to perform based on the exist
ing data.

Appendices

Detailed pages of results that would ‘clog up’ the main report or background material such as leaflets relating to the test equipment.

1.4.3 Example report

An example report is presented here relating to a simple alternator test where its actual output is to be compared to the rated output. Minimal details are included so as to illustrate the main points.

Introduction

A ‘Rotato’ 12V alternator was tested under normal operating conditions to check its maximum output. The manufacturer’s specifications stated that the alternator, when hot, should produce 95A at 6000 rev/min.

Test criteria

● Start at room temperature.
● Run alternator at 3000 rev/min, 30A output for 10 minutes.
● Run alternator at 6000 rev/min, maximum output. Check reading every 30 seconds for 10 minutes.
● Run alternator at 6000 rev/min, maximum output for a further 20 minutes to ensure that output reading is stable.

Facilities/resources

A ‘Krypton’ test bench model R2D2 was used to drive the alternator. The test bench revcounter was used and a ‘Flake’ digital meter fitted with a 200A shunt was used to measure the output. A variable resistance load was employed.

Test procedures

The alternator was run for 10 minutes at 3000 rev/min and the load adjusted to cause an
output of 30A. This was to ensure that it was at a nominal operating temperature. The normal fan was kept in place during the test. Speed was then increased to 6000 rev/min
and the load adjusted to achieve the maximum possible output. The load was further adjusted as required to keep the maximum possible output in case the load resistance changed due to temperature. Measurements were taken every 30 seconds for a period of 10 minutes.

Measured results

Speed held constant at 6000 ( 200) rev/min. Room temperature (18°C).

To ensure that the alternator output had stabilised it was kept running for a further 20 minutes at full output. It continued to hold at 96A.

Analysis of results

Figure 1.2 shows the results in graphical format.

Conclusions

The manufacturer’s claims were validated. The device exceeded the rated output by 6% at the start of the test and under continuous operation at full load, continued to exceed the rated output by 1%. The maximum duration of this test was 20 minutes. It is possible, however, that the device would increase in temperature and the output may fall further after prolonged operation. Further tests are necessary to check this. Overall the device per-
formed in excess of its rated output.

Knowledge check questions

To use these questions, you should first try to answer them without help but if necessary, refer back to the content of the chapter. Use notes, lists and sketches as appropriate to answer them. It is not necessary to write pages and pages of text!
1. State the meaning of the terms ‘fault’ and ‘symptom’.
2. Explain how to reduce the risk of a short circuit when testing electrical systems.
3. List the main headings that could be used for a standard report.
4. State the two main pieces of knowledge necessary to diagnose faults.
5. Describe the potential dangers of running an engine in an enclosed space without exhaust extraction.