The clear identification of technical performance faults for junior gymnastic coaches is the most important step in skillful performance development of young players and reach the peak of competitive standard triangle. Accordingly, The researcher depends in the observation of technical performance of the two skills on Gangsted and Beveridge’s models as an observation model. Which depend on the timed and place sides of skillful performance. Also he depends on Hay and Ried’s model which is one of the best discussions for qualitative analysis with biomechanics to determine technical performance faults and identifying the relative importance of the two skills technical performance faults (Under Study).The role of the researcher in his serious, Scientific attempt to put a training solutions for the two skills technical performance faults (Under Study) Came after technical performance observation, identifying these faults and determine the priority of these faults in related to the skillful performance.
Method: The researcher used the descriptive method by case study. The sample involved the juniors (under 9 Years) of the Egyptian Gymnastic Federation in Assiut and Mina.
The Sample was purposive, Consists of 12 Juniors and 20 Coaches, The Consistency was made between for subjects on the basic variables (age- weight- height, some physical characteristics that effected on performance and skillful performance). The researcher designed the observation model by qualitative analysis Hay and Ried’s models and an assessment form for skillful performance of the two skills (under study), He uses the arithmetic means, standard deviation, percentage, standard error, average percentage degree.
Results:
Arithmetic means, Standard deviation and the percentage of error at technical performance phases of back- hand spring skill which followed by back somersault straight over floor exercise apparatus.
Average
phase percentage Percentage % standard deviation arithmetic means Total degrees estimated degree The errors of technical performance phases of back hand spring:

62.53

54.88

70.17 1.34

1.10 2

1.18 39.9

23.65 2.85

2.15 First Legs- Pushing and back- up hand swing phase.
2- Foot- land pushing during body leaning backward.

67.44
69.91

64.96
1.24

1.116
1.65

1.72
33.02

34.44
2.54

2.46 Second: Per- Flight Phase
1- Increase in Players body height during per- flight.
2- bend hips joint during per- flight
* Results showed that the percentage of the effect degree of technical aspects in leg- push and back- arms, upraise phase is (54. 88%- 70.17%) and the average of faults (62.53%).
Discussion: Results indicated that Hay and Ried’s Models Contribute to faults identification and determine the most dangerous one on the performance, as it cleared that the fault of players body height increase during flying phase is most dangerous on the performance. And the fault of foot- groung un push during body back is the most dangerous fault effected the performance of leg- pushing and up- back work and forward hand spring phase.
Reference:1- Duane, v.Knudson, Criag,S.Morrison1997: Qualitative analysis of human movement, (15- 19) U.S.A.